The Saclay Nuclear Physics Division by Nicolas Alamanos

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Nuclear Physics Nuclear Physics News is published on behalf of the Nuclear Physics European Collaboration Committee (NuPECC), an Expert Committee of the European Science Foundation, with colleagues from Europe, News America, and Asia. Volume 15/No. 3

Editor: Gabriele-Elisabeth Kömer Editorial Board J. D’Auria, Vancouver W. Kutschera, Vienna R. F. Casten, Yale M. Leino, Jyväskylä T. W. Donnelly, MIT Cambridge R. Lovas, Debrecen A. Eiró, Lisbon S. Nagamiya, Tsukuba M. Huyse, Leuven (Chairman) C. Trautmann, Darmstadt Editorial Office: Physikdepartment, E12, Technische Universitat München, 85748 Garching, Germany, Tel: +49 89 2891 2293, +49 172 89 15011, Fax: +49 89 2891 2298, E-mail: [email protected]

Correspondents Argentina: O. Civitaresse, La Plata; Australia: A. W. Thomas, Adelaide; Austria: H. Oberhummer, Vienna; Belgium: C. Angulo, Lauvain-la-Neuve; Brasil: M. Hussein, São Paulo; Bulgaria: D. Balabanski, Sofia; Canada: J.-M. Poutissou, TRIUMF; K, Sharma, Manitobu; C. Svensson, Guelph: China: W. Zhan, Lanzhou; Croatia: R. Calpar, Zagreb; Czech Republic: J. Kvasil, Prague; Slovak Republic: P. Povinec, Bratislava; Denmark: K. Riisager, Årnus; Finland: M. Leino, Jyväskylä; France: G. De France, GANIL Caen; B. Blank, Bordeaux; M Guidal, IPN Orsay; Germany: K. D. Gross, GSI Darmstadi; K. Kilian Jülich; K. Lieb, Göttingen; Greece: E. Mavromatis, Athens; Hungary: B. M. Nyakó, Debrecen; India: D. K. Avasthi, New Delhi; Israel: N. Auerbach, Tel Aviv; Italy: E. Vercellin, Torino; M. Ripani, Genova; L. Corradi, Legnaro; D. Vinciguerra, Catania; Japan: T. Motobayashi, RIKEN; H. Toki, Osaka; Malta: G. Buttigieg, Kalkara; Mexico: J. Hirsch, Mexico DF; Netherlands: G. Onderwater, KVI Groningen; T. Peitzmann, Utrecht; Norway: J. Vaagen, Bergen; Poland: T. Czosnyka, Warsaw; Portugal: M. Fernanda Silva, Sacavém; Romania: A. Raduta, Bucharest; Russia: Yu. Novikov, St. Petersburg; Spain: B. Rubio, Valencia; Sweden: P.-E. Tegner, Stockholm; Switzerland: C. Petitjean, PSI Villigen; United Kingdom: B. F. Fulton, York; D. Branford, Edinburgh; USA: R. Janssens, Argonne; Ch. E. Reece, Jefferson Lab; B. Jacak, Stony Brook; B. Sherrill, Michigan State Univ.; H. G. Ritter, Lawrence Berkeley Laboratory; S. E. Vigdor, Indiana Univ.; G. Miller, Seattle.

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Vol. 15, No. 3, 2005, Nuclear Physics News 1 GNPN Contents.fm Page 2 Thursday, August 11, 2005 3:02 PM

Nuclear Physics Volume 15/No. 3 News

Contents Editorial...... 00 Laboratory Portrait The Saclay Nuclear Physics Division by Nicolas Alamanos ...... 00 Feature Articles A Relativistic Symmetry in Nuclei by Joseph N. Ginocchio...... 00 Exploding Stars, Neutrinos, and Nucleosynthesis by Gail McLaughlin...... 00 Facilities and Methods High-Resolution Gamma-Ray Spectroscopy at TRIUMF-ISAC by Greg Hackman...... 00 Radioactive Ion Beam Facility in Brazil (RIBRAS) by R. Lichtenthäler, A. Lépine-Szily, V. Guimarães, and M.S. Hussein...... 00 BEN@ECT*: The New 1Tflop/s Computing Facility at The European Centre for Theoretical Studies in Nuclear Physics and Related Areas by Pierfrancesco Zuccato...... 00 Recent Achievements in Multinucleon Transfer Reaction Studies at LNL by Lorenzo Corradi and Giovanni Pollarolo...... 00 Meeting Reports Atomic Nuclei at the Extreme Values of Temperature, Spin, and Isospin, XXXIX Zakopane School of Physics, 31 August–5 September 2004, Zakopane, Poland by Angela Bracco ...... 00 Symposium on “Atomic High-Precision Mass Spectrometry” by Klaus Blaum and Lutz Schweikhard Report on the 15th Panhellenic Symposium on Nuclear Physics by Georgios A. Lalazissis News and Views ...... 00 Calendar ...... 00

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editorial

The need for Ion Accelerators in Non-Nuclear Physics Fields

When ion implantation started to along the ion trajectory. There are no including commercial membrane pro- replace diffusion as a means for dop- other means by which similar high- duction and proton-therapy for eye ing semiconductors, the market leader energy densities can be placed that tumors. The versatility and the high- hesitated too long to install the new deep in the bulk of materials. The duty cycle of the ISL machine provide technology and was outrun by others. large ion range in combination with most suitable beam conditions for Admittedly, hardly anyone at that time the small track diameter of a few irradiation experiments in materials had envisioned the huge impact ion nanometers play a key role for science. The decision to shut down implantation would have on the semi- numerous applications. Research per- cannot be understood on the basis of conductor industry, finally becoming formed at large accelerator facilities, scientific arguments because a recent a key technology in complex produc- mainly in Europe but with increasing evaluation rated the performed tion lines. This success is directly intensity also in Japan, China, and research as excellent. linked to the comprehensive under- India, is significantly improving the Why is successful exploitation of standing of ion–matter interaction pro- understanding of basic electronic energetic ion beams with spin-off cesses achieved at accelerators provided excitation processes, track formation, applications in many disciplines not by the nuclear physics community. and ion-induced degradation, and the sufficient to justify the continued Theoretical models and simulation tailoring of materials properties. The operation of a dedicated facility? Can codes (such as TRIM) predicting the number of different topics addressed these activities only coexist with effect of elastic collision cascades is enormous, ranging from studies of nuclear physics? Even more impor- were indispensable for optimizing materials response to extreme radia- tant, what will happen if the perma- production performances and develop- tion conditions (reactor material, nent striving for higher energies in ing ion beam technology in the low- nuclear waste storage), dating of geo- nuclear and particle physics contin- energy regime (up to several hundred logical minerals, fabrication of nano- ues, resulting in shutting down more keV per nucleon). Many standard objects, simulation testing of cosmic and more smaller accelerators? How techniques, such as SIMS, PIXE, rays on electronic devices for space, can the ion-beam community respond RBS, ERDA, and AMS are nowadays to radiation effects on biological to additional tasks linked, for exam- in regular use, mainly for materials cells. Extensive basic research in this ple, to the future fusion reactor analysis, with the general trend to field has been essential for the devel- project, ITER, or to incineration and smaller beam dimensions including opment of hadron tumor-therapy, transmutation of reactor waste in focused ion beams for producing which is now emerging with several accelerator-driven reactor systems? nanostructures. dedicated facilities in the construc- At present, the beamtime schedule at The continuous drive of the tion or planning phase. large facilities is complex and usually nuclear physics community to higher Considering the broad potential of overbooked. Experimental access energies at larger accelerator facili- swift heavy ions, the closing of the ion involves slow proposal evaluation ties offered new possibilities for beam facility (Ionenstrahllabor ISL) at processes, a situation which is cer- research activities in application- the Hahn-Meitner Institute in Berlin, tainly not adequate for materials oriented fields. In contrast to low- announced for the end of 2006, caused science, in particular if industrial energy ions, ion-matter interaction a shock. After termination of the partners are involved. A common with beams above about 1–3 MeV per nuclear physics program, this machine European effort may help to improve nucleon are dominated by electronic has been exclusively devoted to basic access conditions by interconnecting processes with a huge energy deposition materials research and applied activities high-energy accelerators of, for

The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.

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example, GANIL, GSI, Legnaro, Munich, and Orsay to a virtual facility and setting up special arrangements such as beam-quota allocations and independent proposal and program committees. In any case, the risk that essential needs of the ion-beam community in applied disciplines will not be covered adequately in the future has to be seen as very large. WALTER ASSMANN CHRISTINA TRAUTMANN MARCEL TOULEMONDE LMU Munich GSI, Darmstadt CIRIL, Caen CHRISTINA TRAUTMANN GSI Darmstadt, Germany

2 Nuclear Physics News, Vol. 15, No. 3, 2005 The Saclay Nuclear Physics Division

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The Saclay Nuclear Physics Division

The Nuclear Physics Division along with other parameters of the target chamber with a rotating target (Service de Physique Nucléaire, SPhN) effective force, such as the spin-orbit system dedicated to the study of the of DAPNIA at Saclay in France is part coupling or the pairing term, it will structure and production of heavy and of the fundamental research divisions need to be readjusted for nuclei far super-heavy elements. SPhN is now of the CEA (Commissariat à l’Energie from stability. participating in the development of Atomique). Its programs cover a broad SPhN is involved in the study of experimental devices designed to range of topics in Nuclear Physics from the structure of light exotic nuclei measure with better efficiency, energy low to high energies. They include the such as 6–8He, 10–11C, 27Ne and in the resolution, and granularity recoil par- study of the structure and dynamics of study of shape coexistence in Kr iso- ticles (MUST2) and gamma rays the nucleus, the structure of the topes. The experiments are performed (AGATA) produced in reactions nucleon, and the search for phase tran- at GANIL with beams delivered by induced by radioactive beams. sitions of nuclear matter. SPhN also the SPIRAL or SISSI facilities. It is Nuclear structure physicists unani- contributes to measurements and mod- also involved in experiments at mously support the SPIRAL2 project, eling of specific nuclear reactions Jyväskylä (Finland) to obtain informa- which aims to accelerate from 2009 related to nuclear waste transmutation. tion on the spectroscopy of transfer- radioactive beams produced by fission Furthermore, physicists apply their mium nuclei and especially on the of uranium, and which will give access knowledge, competence, and techniques structure of 251Md. Near-barrier and to beams of heavier nuclei than those to the development of innovative sub-barrier fusion of light unstable obtained from the current SPIRAL facil- nuclear energy cycles, to the produc- nuclei and their respective stable iso- ity. Medium- and long-range plans tion of neutron and radioactive beams topes with 238U targets are studied at encompass participation in the new GSI and to the decommissioning of nuclear Louvain La Neuve (Belgium). Among project R3B and in elaborating the phys- installations. The research activities the most significant experimental ics case for the European EURISOL take place within strong national and results, one can mention the remarkable project as well as in participating in its international collaborations involving sensitivity of inelastic scattering to the design and construction. the academic world and enabling the halo structure of 6He, studies on the 8 selection and training of high-quality structure of He (Figure 1), the first Nuclear Phase Transitions students and post-doctoral researchers. experimental evidence for a shape Heavy ion collisions offer the pos- 72 isomer in N=Z nuclei ( Kr) supporting sibility to create nuclear matter in the The Structure of the Nucleus the predicted scenario of prolate-oblate laboratory under extreme conditions The objective of experiments in shape coexistence in this mass region of pressure and temperature. The pur- this area is to test and improve the and, by combining conversion-elec- pose of our activities in this domain is descriptive and predictive power of tron and gamma-ray spectroscopy, the twofold: the study of the liquid–gas nuclear structure models in the most first study of the structure of an odd phase transition in nuclei at relatively 251 extreme conditions with regards to transfermium nucleus Md (Figure 2). low incident energies and the search nuclear isospin, angular momentum, The experiments were realized for the quark-gluon plasma at very mass, and temperature. Most of these with experimental devices constructed high energies. experiments concern very unstable within the framework of national and At relatively low incident energies, nuclei for which new phenomena such international collaborations and with SPhN is involved in studies of the as very diffuse nuclear surfaces, clus- the participation of DAPNIA technical dynamics of heavy-ion collisions that tering, low-lying resonances, or new divisions. This encompasses participa- aim at obtaining information on the magic shells appear that are not pre- tion in the construction of the silicon equation of state of nuclear matter and dicted by present models. The isospin strip detector array MUST, of the seg- concomitantly on the liquid–gas phase dependence of the effective nucleon- mented clover Ge detector EXOGAM, transition. This is an ingredient of nucleon force is a key ingredient of of the focal plane detection system of nuclear dynamics governing stellar pro- the models. One may expect that, the VAMOS spectrometer and of the cesses such as supernova explosions.

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The main experimental tool for these studies is the 4π multiparticle INDRA detector, built with strong contributions from DAPNIA’s technical divisions. One of the quantities of interest in these collisions is the excitation energy of the nuclei formed before any particle emission. An outstanding result in this domain is the direct measurement of the thermal excitation energy of the primary fragments produced in central collisions between 32 and 50MeV/A. The experimental results are well reproduced by statistical multi- fragmentation models. These finding, combined with other experimental signatures, allow a better understanding of nuclear matter dynamics below 5MeV/A excitation energy. At high temperatures and/or densities, QCD predicts a new form of matter, consisting of an extended volume of deconfined quarks, antiquarks, and gluons called the quark- gluon plasma (QGP). The aim here is to study the properties of this plasma, which is thought to have existed a few microseconds after the Big Bang. SPhN participates in this search. Among the signatures of the QGP one of the most promising is the color Figure 1. To investigate the structure of exotic nuclei with direct reactions screening of heavy resonances (J/ψ and in inverse kinematics, the MUST detector has been developed Y) formed by pairs of heavy quarks (collaboration IPN Orsay, SPhN and SPN Bruyères le Chatel). A typical and antiquarks. We study these reso- experimental arrangement is presented (top). In particular, it was used nances through their decay into pairs with the Spiral 8He beam at 15.6 MeV/nucleon impinging on proton target. of muons in two experiments: PHENIX A complete kinematical reconstruction of the induced direct reactions is with the accelerator RHIC at (BNL) achieved via the identification of the light recoiling particle in the MUST and ALICE at the LHC (CERN). array in coincidence with the heavy reaction partner detected in a wall of These two experiments use a dimuon plastic scintillator. Two beam tracking detectors, CATS developed by spectrometer for the detection of reso- DAPNIA, are used to reconstruct event by event the trajectory of the nances. SPhN has contributed to the incident particles. The energy versus scattering angle spectrum of the electronics of one of the dimuon arms particles detected in MUST is shown (bottom). The kinematical loci of the PHENIX experiment and is indicate the elastic and inelastic scattering to the unbound first 2+ excited actively participating in the construction state of 8He (3.6 MeV) and the one- and two-nucleon transfer reactions of the dimuon arm for the ALICE 8He(p, d), 8He(p, t). experiment (Figure 3).

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detector show that the production rate of high-transverse momentum pions is suppressed in Au+Au collisions as compared to p+p or d+Au collisions. This result is compatible with suppression in a dense colored medium and could be the signature for the QGP formation. ALICE is an experiment at the LHC (CERN), which is in the course of preparation and that will take its first data in 2008 at an energy about 30 times higher than that of PHENIX (5.5 TeV). It is anticipated that the existence of the QGP will be firmly established at RHIC and its detailed properties studied at ALICE/LHC in the forth- coming years.

The Structure of the Nucleon SPhN is involved in two experimental programs both using electromagnetic probes, one to obtain information on the spin carried by the gluons in the proton (COMPASS at CERN) and the other to extract information on generalized parton distributions by means of deeply virtual Compton scattering (CLAS at JLAB). The contributions of quarks (∆Σ) and gluons (∆G) to the spin of the Figure 2. Top: Gamma-ray spectrum obtained in the Coulomb excitation of a nucleon are accessible by using a 4.5 MeV/u 74Kr beam from SPIRAL taken with the EXOGAM spectrometer at polarized lepton beam and a polarized GANIL. The intensities observed for the different states allow extracting static nucleon target. Recent experiments at and transitioning quadrupole moments and confirm the supposed shape coexistence CERN (SMC) and at SLAC, with scenario. Bottom: First observation of a rotational band in an odd-mass strong participation by SPhN, have Transfermium nucleus. The spectrum was taken with the Jurogam spectrometer established that the contribution of the at the University of Jyväskylä and obtained by tagging the gamma rays with the quarks to the spin of the nucleon is alpha decay of 251Md in the focal plane of the RITU gas-filled separator. small. These results have been complemented by the HERMES experiment at DESY and it is now widely PHENIX is currently taking data at available soon. A striking result accepted that the quark intrinsic spin con- RHIC at nucleon-nucleon collision obtained recently is the jet suppression tributes only a small fraction (20–30%) to energy of 200 GeV. Results on J/ψ observed at large transverse momen- the total nucleon spin. These results agree production in Au-Au collisions will be tum. Indeed, data from the PHENIX with recent QCD calculations.

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The main goal of the COMPASS or the gluons. Experimentally, the GPDs In parallel with these experimen- experiment is the measurement of the are accessible through exclusive hard tal activities, the three theorists of gluon polarisation in the nucleon. DAP- reactions. Among these, the simplest SPhN have focused their activities on NIA has contributed to the COMPASS process is deeply virtual Compton the structure of the nucleon and spectrometer by developing and building scattering (DVCS), ep → epγ. One of baryon resonances. Subjects that are 12 micro-strip “micromegas” detectors the first DVCS measurements was particularly studied are the GPDs, the (40×40cm2) (Figure 4) and 24 drift published by the CLAS collaboration form-factors of the nucleon, and reac- chambers (120×120cm2). These detec- at JLAB in 2002. Physicists from tions for the electromagnetic produc- tors are placed in the zone of high particle SPhN have contributed to the mea- tion of photons and mesons in flux, immediately behind the target. Data surement of the spin asymmetry for different kinematic regimes. taken in 2002 and 2003 have been ana- the DVCS process at a beam energy of Today, there are good prospects for lyzed. These data already provide com- 4.2 GeV. New experiments are in powerful electron facilities in the petitive statistics for numerous channels: preparation at JLAB using experimen- United States in particular at JLAB. It

measurement of g1 (better than SMC at tal equipment under construction at is therefore important to continue our small x), semi-inclusive scattering Saclay (Figure 5). The first goal of investigations at JLAB in which, (already comparable to Hermes), coeffi- these exploratory measurements is to thanks to a future increase of the beam cients of the ρ meson spin density matrix, validate the theoretical connection energy to 12 GeV, measurements of the ∆ polarisation of −the (as good as between DVCS and GPDs. GPDs will be carried out in a wider NOMAD) and Λ (much better than NOMAD). However, the main challenge remains the determination of the gluon polarization ∆G/G. At the recent international conferences SPIN04 in Trieste and BARYONS04 at Palaiseau, the first results on ∆G/G from high transverse momentum hadron pairs were presented. QCD also provides predictions for the transversity, which is the probabil- ity of measuring a quark with a spin orientation parallel to that of the nucleon spin when this is perpendicu- lar to the incident beam. Transversity also manifests itself by a structure function that is a new aspect of the quark dynamics in the nucleon. In the years to come the COMPASS experiment will measure the transversity and bring information in this area that is essentially untouched experimentally. Figure 3. Large tracking stations are necessary to cover the solid angle of the The generalized parton distribu- ALICE dimuon spectrometer. The largest ones are visible on the picture, with tions (GPD) allow an exploration of station 3 located inside the dipole magnet and stations 4 and 5 downstream the three-dimensional structure of from it. They consist of cathode pad chambers arranged in slats on carbon nucleons in terms of partons. The fibber supports on both sides of the beam pipe and shielding. Station 3 is shown innovative aspect of these quantities is at its working position. Only the right halves of stations 4 and 5 are shown at their sensitivity to correlations their working positions. Dapnia/SPhN physicists and Dapnia technical divisions between partons, allowing for exam- have been heavily involved in their design and prototype commissioning. ple, to connect them to the total angu- Dapnia is responsible for building one fourth of them and for integrating all of lar momentum carried by the quarks them in the muon spectrometer.

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kinematic range from 2010 onward. In parallel, a team from SPhN is studying the possibility of measuring DVCS with the COMPASS spectrometer at CERN starting also in 2010 in a com- plementary kinematical region.

Physics for Nuclear Energy In the years to come fast neutron reactors will enable the exploitation of the considerable resources offered by uranium 238U as well as by an eventual 232Th fuel cycle. Nevertheless, the

Figure 5. The CLAS/DVCS experiment, to run in the spring of 2005 at Jefferson Lab, will investigate over a large kinematical domain the applicability of the new concept of Generalized Parton Distributions (GPD). A group of SPhN physicists is part of the leading effort to assemble and run this experiment. A forward photon calorimeter is being added in the middle of the CLAS spectrometer, and Figure 4. The COMPASS experiment at CERN has a broad physics program DAPNIA provides the laser focused on the study of the spin structure of the nucleon and on hadron monitoring for the 424 lead-tungstate spectroscopy. The two-stage spectrometer is designed for high particle rates and crystals. The necessary magnetic high resolution tracking. The photo shows one of the Micromegas “doublets” shield for this calorimeter is a consisting in two microstrip detectors oriented perpendicularly, with 1024 superconducting two-coil solenoid strips each covering a 40 × 40 cm2 active area (top). Data taking has started in (this figure), entirely built at DAPNIA 2002, and will last at least until 2010. The first COMPASS preliminary result with an original cryogenic design, on the gluon polarization ∆G/G, measured at a momentum fraction of the gluon together with its controls and safety = xg 0.13 has been obtained from high pT hadron pair data taken in 2002 and system. This is to date the largest 2003. It is compared to HERMES and SMC published results and to theoretical equipment to be inserted within predictions obtained from fits to polarized deep inelastic data (bottom). CLAS.

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management of nuclear waste is an measurements have gained much new applications have triggered a essential condition for the acceptance interest due to the development of renewed interest in neutron-nucleus of nuclear energy by society. In order new activities related to nuclear reactions, in particular for isotopes to progress in these areas and study energy, such as the transmutation of and energy regions that are essential new means of producing nuclear energy, nuclear waste, the thorium-based for the development and design of the neutron production through spallation nuclear fuel cycle, and ADS. These these concepts. process should be carefully studied and precisely modeled. New sets of neutron induced cross-sections are also needed for many isotopes (especially those present in waste) under various types of reactor neutron fluxes. Our activities in this domain are focused along three major lines: spallation studies, neutron cross-section measurements, and application-oriented modeling. The goal of the spallation studies is to achieve a complete understanding of spallation reactions with experiments covering a wide range of channels. An SPhN group is participating in spallation residue cross-section measurements at the relativistic heavy ion facility of GSI (Darmstadt, Germany). A new experimental program is now under development (SPALLADIN) with the aim of performing more exclusive spallation measurements by measuring spallation residues and evap- orated light particles in coincidence in order to obtain information on the de- excitation stage of the reaction. These experimental studies are complemented by theoretical development of high-energy spallation models Figure 6. Mass distribution at several energies (top) and examples of isotopic (INCL4). These models, once vali- distributions at 1 GeV (bottom) of spallation residues produced in p+Fe dated with a wide set of experimental reactions measured using the reverse kinematics technique with the Fragment data, are incorporated in high-energy Separator at GSI (collaboration SPhN – GSI – IN2P3 – Santiago de transport codes such as LAHET3 or Compostella University). The experimental results are compared with MCNPX and used to evaluate quanti- calculations using the Intra-nuclear Cascade model, INCL4, developed by the ties relevant to ADS design (Figure 6). group in collaboration with the University of Liège, followed by two different It is foreseen that these studies will be de-excitation models: the solid line is obtained with a standard evaporation continued at the planned R3B relativ- whereas the dashed line comes from a de-excitation code in which the istic heavy ion facility at GSI and production of light fragments originates from an asymmetrical fission mode within the framework of the NUSTAR competing with classical evaporation. These results have been used to compute collaboration. the impurity production in an Accelerator-Driven System window. Recoil In recent years, high-resolution velocities have also been measured and allow assessing of damage due to atom neutron-induced reaction cross-section displacements in such a window.

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232 suitable for measurements with a low Th(n, ) CERN-nTOF signal-to-background ratio, as in the 3 10 case of radioactive or low mass sam-

232Th(n, ) ples. SPhN is also involved in the neu- scattered photons radioactivity tron time-of-flight facility Gelina at Geel for carrying out both neutron cap- 102 ture and transmission measurements. In addition to the energy-dependent cross-section measurements, integral neutron-induced cross-sections are investigated by SPhN groups within 101 the Mini-Inca project. This project aims at determining experimentally the optimal conditions for the trans- count rate (counts/dlnE/bunch) mutation of minor actinides in high- Q1 100 intensity, highly thermalized neutron 0 1 2 3 4 5 6 10 10 10 10 10 10 10 fluxes. neutron energy (eV) Furthermore, SPhN is involved in the measurement of neutron flux and actinide incineration rates inside the liq- 20 uid lead-bismuth spallation target within the European MEGAPIE experiment 15 (PSI, Switzerland). The MEGAPIE project is the first experimental demon- stration of a 1MW liquid Pb-Bi spalla- 10 tion target coupled to a high intensity (1.5mA) proton accelerator. This experiment will take place in 2006. 5 In parallel with the aforemen- tioned experimental activities, some count rate rate (counts/dlnE/bunch) count fundamental and applied modeling 0 4.8 103 4.9 103 5.0 103 5.1 103 activities have been developed. This neutron energy (eV) expertise was developed to simulate Figure 7. The n_TOF collaboration has recently built and exploited a new and characterize neutron fluxes inside neutron time-of-flight facility at CERN in the frame of a shared cost RTD action the experimental Mini-Inca channels. of the Fifth EU Framework Program. Since the final commissioning, a scientific It is now applied to calculations of program of measurements of neutron capture and fission cross-sections of innovative nuclear systems for nuclear actinides, long-lived fission fragments and other isotopes relevant for nuclear waste transmutation, intensive neutron technology and nuclear astrophysics, has been scheduled in a first phase from sources based on spallation and photo- 2001 to 2004. The figure shows an example of the count rate spectrum of the nuclear reactions, radioactive nuclear 232Th(n,γ) capture cross-section experiment at n_TOF at CERN, measured with beam production scenarios, character- neutron insensitive deutered benzene gamma-ray detectors. The program for a ization of nuclear waste barrels, second phase of measurements at CERN is currently in preparation. production of neutron-rich fission fragments, and so on, in close cooperation with the LANL (U.S.). SPhN has been involved from the CERN. The strength of nToF lies in its These modeling tools are based beginning in the construction of the very high instantaneous neutron flux on a Monte Carlo technique allow- new time-of-flight facility nToF at making the nToF facility particularly ing realistic geometry and material

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specifications in 3-D. When avail- This expertise led us to undertake medical diagnostic and treatment able, the evaluated data libraries are modeling related to the decommis- purposes. used for multiparticle–nucleus inter- sioning of nuclear installations such The Service de Physique Nucléaire actions and transport calculations. as particle accelerators and research is part of the national basic research Otherwise recent nuclear models are or industrial nuclear reactors, in col- community and contributes to the applied to simulate different processes laboration with DAPNIA/SDA. We excellence of French research while of interest including time-dependent expect these activities to be pursued actively participating in the funda- evolution of nuclear fuel and/or irra- in the future within the framework of mental missions of the Commissar- diation/production targets. These collaboration with the valorisation iat à l’énergie atomique. activities serve as direct evidence of DAPNIA/cell. Finally, among emerg- the link between knowledge of fun- ing activities we would like to quote damental nuclear physics and soci- participation in Monte Carlo simula- NICOLAS ALAMANOS ety-related problems. tions of emission tomography for Saclay

8 Nuclear Physics News, Vol. 15, No. 3, 2005 feature article

A Relativistic Symmetry in Nuclei

Query Sheet Q1 AU: what is?

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A Relativistic Symmetry in Nuclei

JOSEPH N. GINOCCHIO Theoretical Division, Los Alamos National Laboratory Los Alamos, NM 87545, USA

Introduction the non-relativistic limit, then the Schrödinger equation More than thirty years ago it was observed that certain will be a good approximation to the Dirac equation. quantum energy levels in atomic nuclei were almost degen- The Dirac equation has positive energy eigenfunctions erate in energy [1]. The states that are almost degenerate and negative energy eigenfunctions. The former are the eigen- (quasi-degenerate) have different radial quantum numbers functions of the particles and the latter are the eigenfunctions and different orbital angular momenta, features that made of the anti-particles. A Dirac eigenfunction will then have the reason for their degeneracy difficult to penetrate. twice as many components as a Schrödinger eigenfunction. In The dynamics of neutrons and protons in nuclei have the non-relativistic limit, the “upper” component of the posi- been successfully treated non-relativistically. Therefore it tive energy eigenfunctions will become the Schrödinger has come as a surprise that this quasi-degeneracy of quan- eigenfunctions for the particles and the “lower” component tum states in heavy nuclei, which has eluded understanding will become vanishingly small, whereas the “lower” compo- for about thirty years, can be explained by a relativistic nent of the negative energy eigenfunctions will become the symmetry [2]. Schrödinger eigenfunctions for the anti-particles and the “upper” component will become vanishingly small. Likewise, in the Dirac equation two types of potentials The Nuclear Shell Model are possible, one a relativistic scalar and one a relativistic Atomic nuclei are well described by nucleons moving in vector. The sum of the two potentials dominate the dynamics a non-relativistic mean field with residual interactions that of the particles whereas the difference of the two dominate induce correlations between the nucleons. The dynamics of the the dynamics of the anti-particles. nucleons in the orbits are described by the non-relativistic Schrödinger equation. For spherical nuclei the quantum numbers of the orbits in the mean field are the radial quan- Symmetries of the Dirac Hamiltonian tum number, n, the orbital angular momentum, l, and the When the scalar potential and vector potential are equal total angular momentum, j, which is the sum of the orbital the Dirac Hamiltoian has spin symmetry. This means that angular momentum and the spin; (n, l, j) for short. The the eigenfunctions that differ in the orientation of the spin orbits that are quasi-degenerate in energy are (1, 0,1/2) and will be degenerate in energy. That is, the orbits (n, l, (0, 2, 3/2), (1, 1, 3/2) and (0, 3, 5/2), and so on. That is, the j = l + 1/2) and (n, l, j = l − 1/2) will have the same energy. orbit with (n, l, j = l + 1/2) will be quasi-degenerate with the These states are spin doublets because the energy does not orbit (n − 1, l + 2, j = l + 3/2); that is the radial quantum num- depend on the orientation of the spin. This symmetry bers will differ by one unit, the orbital angular momenta occurs in hadrons [3]. will differ by two units, and the total angular momenta by When the scalar potential is equal to the vector poten- one unit. tial, but opposite in sign, there is another symmetry of the For deformed nuclei the orbits that are quasi-degenerate Dirac equation. This symmetry is called pseudospin sym- have angular momentum projection along the symmetry metry. The states that are degenerate have exactly the radial axis differing by two units and total angular momentum quantum numbers and orbital angular momenta of the projection differing by one unit. quasi-degenerate states that have been observed in nuclei and are pseudospin doublets. The Dirac Hamiltonian The Dirac equation, not the Schrödinger equation, must Relativistic Mean Field be used to describe the relativistic dynamics of nucleons Relativistic models of nuclei include nuclear field theories moving in a relativistic mean field. In the limit that the rela- with nucleons interacting by the exchange of mesons on the tivistic mean field is small compared to the kinetic energy, one hand and nucleons interacting with relativistic interactions.

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These models are difficult to solve exactly but have been 208Pb. in Figure 1a is the upper amplitude, g(r), for the (n =1, solved in the relativistic mean field approximation, which l=0, j=1/2) state (solid line) and the (n=0, l=2, j =3/2) state reduces to a Dirac Hamiltonian with the scalar and vector (dashed line). These radial amplitudes have very different in potentials determined self-consistently [4]. The resulting shapes. However, the lower amplitudes, f(r), are almost iden- scalar and vector potentials are opposite in sign and tical as seen in Figure 1b. In Figure 1c is the upper ampli- Q1 approximately equal in magnitude. Thus the symmetry, tude, g(r), for the (n=2, l=0, j=1/2) state (solid line) and the which was observed in the nuclear states more than thirty (n=1, l=2, j=3/2) state (dashed line). Again these radial years ago, is pseudospin symmetry, a symmetry of the amplitudes have very different shapes. However, the lower Dirac Hamiltonian. amplitudes, f(r), are almost identical, as seen in Figure 1d. As the radial quantum number increases, the lower amplitudes become more similar, implying that pseudospin conservation Predictions of Pseudospin Symmetry improves as the binding energy decreases, Amplitudes Pseudospin symmetry also imposes conditions on the upper One of the predictions of this pseudospin symmetry is amplitudes but these are more complicated, involving differen- that the spatial amplitudes of the lower components for the tial equations between the amplitudes. However, these condi- two states in the degenerate doublets should be equal in mag- tions are approximately satisfied as well and improve as the nitude. We have tested this condition by examining the lower binding energy decreases [6] just like the lower amplitudes. amplitudes of the Dirac eigenfunctions determined in relativ- A survey of other states in both deformed and spherical istic mean field calculations of nuclear spectra using realistic nuclei for pseudospin symmetry in both upper and lower vector and scalar potentials [5]. In Figure 1 we show an components show that pseudospin symmetry is approximately example of the amplitudes of the lower components of two conserved and the conservation increases as the binding states of a pseudospin doublet in in the spherical nucleus energy decreases [7].

0.4 0.01

0.3 a) b) 0 0.2

g(r) 0.1 f(r) -0.01 (fm) -3/2 (fm) -3/2 0 -0.02 -0.1

-0.2 -0.03 0 5 10 15 0 5 10 15 r (fm) r (fm) 0.5 0.02

0.4 0.01 c) d) 0.3 0 f(r) g(r) 0.2 f(r) -0.01 (fm) -3/2 (fm) -3/2 0.1 -0.02

0 -0.03

-0.1 -0.04

-0.2 -0.05 0 5 10 15 0 5 10 15 r (fm) r (fm) Figure 1. The upper amplitudes, g(r), and lower amplitudes, f(r), versus the radius r.

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Magnetic Dipole and Gamow Teller Transitions and scalar potentials in nuclei are almost equal in magnitude Magnetic dipole transitions between pseudospin doublets and opposite in sign [15], which is consistent with approxi- are forbidden non-relativistically because the states in the dou- mate pseudospin symmetry. The difference in sign comes blets have angular momentum differing by two units and the from the fact that the quark condensate of the vacuum is dipole can only change the angular momentum by at most one negative. unit. However, these transitions are allowed relativistically. If pseudospin symmetry is conserved, then, if the mag- Future Study netic moment of the states in the doublet is known, the This connection with QCD suggests that there may exist magnetic dipole transition between the pseudospin doublets a more basic rationale for pseudospin symmetry in nuclei can be determined [8]. For example, using the magnetic based on the interaction between quarks that needs to be 39 moment of the ground state of Ca, the predicted magnetic explored. For example, one question is “Why is pseudospin dipole transition agrees with the measured transition within symmetry valid for nuclei, whereas spin symmetry is valid experimental error. A global analysis of such transitions for for hadrons?” many nuclei shows that these predictions are approximately valid [9]. Similar relations hold for Gamow Teller transitions in beta decay as well. 1. A. Arima, M. Harvey and K. Shimizu, Phys. Lett. B, 30 (1969) 517; K. T. Hecht and A. Adler, Nucl. Phys. A, 137 (1969) 129. Nucleon-Nucleus Scattering 2. J. N. Ginocchio, Phys. Rev. Lett., 78 (1997) 436. The elastic scattering of medium energy nucleons from 3. P. R. Page, T. Goldman, and J. N. Ginocchio, Phys. Rev. Lett., 86 (2001) 204. nuclei can described successfully with a relativistic optical 4. B. D. Serot and J. D. Walecka, in Advances in Nuclear model with complex scalar and vector potentials. The Physics, edited by J. W. Negele and E. Vogt, Vol. 16 (Plenum, scalar and vector potentials determined by fitting the scat- New York, 1986); P.-G. Reinhard, Rep. Prog. Phys., 52 tering data are approximately equal in magnitude but differ- (1989) 439. ent in sign even though they are complex [10]. 5. J. N. Ginocchio and D. G. Madland, Phys. Rev. C, 57 (1998) 1167. The scattering amplitude consists of two parts, one 6. J. N. Ginocchio, Phys. Rev. C, 66, (2002) 064312. independent of pseudospin symmetry and one pseudospin 7. J. N. Ginocchio, A. Leviatan, J. Meng, and S.-G. Zhou, Phys. dependent. The pseudospin dependent amplitude has been Rev. C, 69 (2004) 034303. 8. J. N. Ginocchio, Phys. Rev. C, 59 (1999) 2487. extracted from the measured spin polarization and the spin 9. P. von Neumann-Cosel and J. N. Ginocchio, Phys. Rev. C, 62 rotation [11,12]. For the scattering angles measured the (2000) 014308. pseudospin dependent amplitude is only 10% of the 10. R. W. Fergerson et al., Phys. Rev C, 33 (1986) 239. pseudospin independent amplitude. For lower energy 11. J. N. Ginocchio, Physical Rev. Lett., 82 (1999) 4599. nucleons, however, the pseudospin breaking increases [13]. 12. H. Leeb and S. Wilmsen, Phys. Rev. C, 62, (2000) 024602. 13. H. Leeb and S. A. Sofianos, Phys. Rev. C, 69, (2004) 054608. 14. J. N. Ginocchio, Lecture Notes in Physics, 641 (2004) 219. Antinucleon-Nucleus Scattering 15. T. D. Cohen, R. J. Furnstahl, D. K. Griegel, and X. Jin, Prog. A nucleon changes into an antinucleon under charge in Part. and Nucl. Phys., 35 (1995) 221. conjugation. Under charge conjugation the scalar potential remains unchanged but the vector potential changes sign. Thus, an antinucleon in a nuclear environment will experience vector and scalar potentials that are approximately equal. This implies spin symmetry. Indeed, spin polarization measured in antinucleon nucleus scattering is consistent with zero, implying spin symmetry [14].

Fundamental Theory of the Strong Interactions and Pseudospin Symmetry Quantum Chromodynamics (QCD), the fundamental theory of the strong interactions, predicts that the vector JOSEPH N. GINOCCHIO

Vol. 15, No. 3, 2005, Nuclear Physics News 3 Exploding Stars, Neutrinos, and Nucleosynthesis

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Exploding Stars, Neutrinos, and Nucleosynthesis Q1 GAIL MCLAUGHLIN

Exploding Stars iron, which is the most tightly bound element. An “onion Supernovae are some of the most violent, energetic ring” structure develops in the star with hydrogen as the events that occur in the universe. The most recent super- outer ring, then helium and the heavier elements, and iron nova in our Galaxy that could be seen from earth was at the core. The iron core is initially supported by degen- Cassiopeia A, which occurred about 1680. This supernova erate electron pressure, as is the case for a white dwarf. As was the explosion that ended the life of a massive star, also the core reaches higher densities electron capture sets in called a core collapse supernovae. Observationally, super- and the core becomes unstable. The inner core quickly novae are divided into two main types, Type I and II, where collapses to nuclear density. At this point matter becomes the classification is based on their spectral features. Type I very incompressible and the core rebounds. When infall- supernovae do not have hydrogen lines in their spectra ing material hits outgoing material a shock wave is whereas Type II supernovae do. Type II supernovae are formed, which begins to propagate outward. Up to this always core collapse supernovae, but only some of Type I point, the explosion has been successfully modeled on supernovae are. large computers. However, the details of how the shock Type Ia and core collapse supernovae are very different ejects the outer layers of the star have never been convinc- objects. A Type Ia supernovae occurs when a white dwarf ingly demonstrated. star, such as a carbon–oxygen white dwarf, is in a binary This should not come as a surprise. The problem of the- system with an ordinary star. The white dwarf star slowly oretically modeling the explosion is difficult because it accretes material from the outer envelope of its companion. combines many areas of physics, such as general relativity, Once sufficient material has been accreted so that the den- hydrodynamics, neutrino, and nuclear physics. Also, the sity or temperature on the white dwarf becomes quite high, energy balance is very delicate. Neutrinos carry away about for example, densities of 2*109 g/cc, a runaway nuclear 99% of the binding energy of the iron core, about 1053 erg. fusion reaction results. The energy released from the fusion Only a small fraction of the total energy goes into the process powers an explosion. Type Ia supernovae are con- kinetic energy of the shock. Finally, constructing detailed sidered to have nearly constant luminosity and are therefore models is computationally very intensive, and the effort used as “standard candles,” meaning that their apparent required for three-dimensional models with sufficient gran- luminosity is a way to judge their distance. Comparing the ularity is still prohibitively large. All of this does not imply, inferred distance with the redshift is one of the ways that however, that we cannot study other aspects of the super- has been used to measure (and discover!) the acceleration nova. In the following we shall see that there are many phe- of the universe. nomena related to supernovae about which we can learn A Type II supernova comes from the explosion that even without yet having a definitive theoretical model of ends the life of a star that has a mass of around ten to thirty the explosion mechanism. times the mass of our sun. Throughout most of their lives, Before we come to this, we would like to complete our stars shine by burning hydrogen to helium, as is happening brief tour of exploding stars. Type Ib and Ic supernovae are right now in the sun. The energy released from the binding also without hydrogen lines, but these are not thermonu- of free nucleons into helium provides the pressure that sup- clear detonations off the surfaces of white dwarfs as one ports the star against gravity. After the sun has exhausted might expect from the name. Instead, Type Ib and Ic are the majority of its hydrogen supply, it will burn helium into core-collapse supernovae, similar to the Type II supernovae carbon and oxygen. The gravitational pressure will not be described earlier, but distinguished by the fact that the pro- sufficient to compress the star to temperatures required genitor lost its hydrogen envelope (Ib) or hydrogen and to burn past oxygen and so the sun will end its life as a helium envelope (Ic) prior to collapse. carbon–oxygen white dwarf. Gamma ray bursts, first discovered more than thirty A more massive star will continue to burn beyond car- years ago, are intense bursts of gamma rays. The astrophys- bon and oxygen and create heavier nuclei all the way to ical origin of these bursts was largely mysterious up until

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shock been produced. Furthermore, all of these types of supernovae produce unique nucleosynthesis products that make ν driven important contributions to the amount and type of elements wind that exist in the solar system today. ν Neutrinos are an essential component for understanding e core collapse supernovae for many reasons, the most obvi- ν ous being that they carry the vast majority of the energy. Q4 e The core formed by the collapse of the star, called a proto- 14 3 ν ν ν ν neutron star, is so hot (100MeV) and dense (10 g/cm ), Q2 µ µ τ τ that not only are the photons trapped but the neutrinos are protoneutron star as well. Neutrinos are produced thermally and are emitted, about 1057 of them, in all three flavors, electron, mu, and tau, as well as their anti-particles. Because neutrinos inter- act only by the weak interactions, they decouple at the surface of the core where the temperature is around 10 MeV– 25 MeV and exit the star in the first tens of seconds. Figure 1. Schematic sketch of a supernova. The neutrinos In contrast, photons do not escape for many hours. Not leak out of the proto-neutron star on a time scale of around only do the neutrinos emerge first but in most cases they 10 seconds, while the shock moves out very quickly, in a may be all that we can detect here on earth. For a supernova fraction of a second. Neutrinos of different energy and in our galaxy the photons may never be seen at all, because flavor decouple at slightly different densities in the proto- most of our Galaxy is obscured by dust. This is the reason neutron star. why, although estimates of the Galactic core collapse supernova rate are around every 50 years or so, the last supernova very recently. Over the last few years the situation is evolv- observed on earth occurred more than 300 years ago. ing very rapidly, as significant amounts of data from satel- Neutrinos from a core collapse supernovae were lites and ground based telescopes are being gathered. detected only once, from Supernova 1987a in the Large Gamma ray bursts can be classified into long and short Magellanic Cloud, by the Kamiokande and IMB detectors. duration bursts. In the 1990s data was taken on the long In the mean time, much larger neutrino detectors are on-line duration bursts, and it was discovered that they have coun- terparts in the X-ray, optical and radio parts of the spectra, 1.00 Pt the “afterglow,” which goes on for days or even months (in Zr 0.50 the case of radio emission) after the initial gamma ray Sn Os Ga Ru Ba Cd Nd Dy burst. More recently, a few cases were discovered that Sr Gd 0.00 Er Pb show a “bump” in the light curve of the afterglow. This Ce Sm bump can be fit to a traditional core-collapse supernovae Yb Ir –0.50 Ge Pd light curve, that is, the kind that is driven by the beta decays ε Y Hf Rh

of nickel and cobalt. In a few cases spectra have been taken log –1.00 La Mo Ag Ho and the spectra look remarkably like those seen in Type Ib Pr Nb Eu –1.50 Tb Au or Ic data. The clear suggestion is that gamma ray bursts Tm come from some sort of unusual core collapse supernova Lu Th –2.00 CS 22892052 Abundances event. Upper Limits U SS rProcess Abundances Nuclear physics plays many roles in all of these events. It –2.50 is nuclear reactions that produce the energy that powers the 30 40 50 60 70 80 90 Atomic Number explosion in Type Ia supernovae. It is the nuclear equation of state that determines the point at which the collapse is halted Figure 2. Observational data from a halo star that shows and the shock wave is formed in core collapse supernovae. It abundances of r-process elements. The line shows the solar is the neutrino scattering reactions that may provide the nec- system distribution. Figure from Cowan and Sneden astro- essary energy to keep the shock wave moving, once it has ph/0409552.

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In addition to explosive burning, there are other types of nucleosynthesis that may occur in core-collapse supernovae, such as rapid neutron capture (or r-process) synthesis. “Rapid” means that the time scale for neutron capture is short compared to the time scale for beta decay. The r-process is responsible for almost half the heavy elements (those with mass number A > 100), including the transuranic elements such as Uranium and Thorium. Although the mechanism for producing these elements has been known since the late 1950s, the astrophysical site remains a mys- tery. Recent observational results of low metallicity halo stars show that the abundance pattern for r-process elements in very old stars is very similar to that observed in our own solar system. This suggests that the same type of event is producing the same elemental pattern over and over again. The neutrino-driven wind of the core supernova is a seductively simple possibility for producing these elements. Supernovae occur on the right time scale in order to Figure 3. This figure shows the rate of neutrino-anti- account for the amount of r-process material present in the neutrino annihilation above a GRB accretion disk in units galaxy. Also, core collapse supernovae begin occurring rel- of eV/cm3/s. The black hole is in the center and the solid atively early on, explaining the presence of r-process ele- lines show the density scale height of the disk. Figure ments in old stars. The neutrino-driven wind occurs after created by Jim Kneller. the first tenths of seconds when the shock has moved far out in the star. The neutrinos continue to impart a small amount of their energy to the material on the surface of the that could potentially record thousands of events from a proto-neutron star and push these free neutrons and protons galactic supernova. Although supernovae are rare, such a out in a wind. The prospects for making the r-process detection is much anticipated. As discussed earlier, neutri- depend on the relative number of free neutrons and protons, nos provide a window into the center of the supernova. Neu- which in turn depends on the relative rate of electron neutrinos will scatter last at the surface of the core, and as a trino and anti-neutrino capture on free nucleons in this result their spectrum reflects the conditions at this point. wind. The electron anti-neutrinos, having decoupled slightly deeper in the core than the electron neutrinos, have Nucleosynthesis slightly higher energy than the neutrinos. The balance of As well as being a unique source of neutrinos, super- the charged current neutrino interactions therefore drives novae are also the site of unique types of element syn- the material neutron rich and creates a potentially viable thesis. Explosive burning in core-collapse supernovae environment for the r-process. occurs as nucleons and nuclei are fused together as the Detailed calculations have shown that the neutrino-driven shock wave from the explosion passes through. This wind comes very close to producing the r-process elements. results in a considerable production of Nickel-56, which One of the reasons that this environment is not completely beta decays first to Cobalt-56 and then to Iron-56. After successful is again related to the neutrinos. An important the beta decay the daughter nucleus decays by emitting a early stage of the r-process involves alpha particles and neu- gamma ray. The decay photon is thermalized as it scat- trons. A successful r-process requires many neutrons per ters off surrounding material and drives the supernova alpha particle. However, if the neutrino flux is large charged light curve. In fact, it is the beta decay lifetimes of these current reactions convert neutrons to protons that immedi- nuclei that determine the timescale of the observed light ately combine with neutrons to form more alpha particles, curve. The iron produced in explosive burning also con- and the number of neutrons per seed nucleus becomes too tributes significantly to the galactic inventory of this small. We must find either find physics missing from our cal- element. culation of the wind, or look to another environment.

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Exotic Supernovae we can guess. In order to account for the “bumps” in the the There have been hints that there is not just one way in light curve that look like standard supernovae, one needs which a core collapse supernovae explodes but instead a nickel, on the order of half a solar mass. So some nickel range of possibilities. As mentioned earlier, some of these must be synthesized in the burst. Does it occur from explo- bursts have spectra that look similar to Type Ib and Ic sive burning as in the standard core collapse supernovae, or supernovae. What makes an “ordinary” core collapse does it come from material ejected from an accretion disk, supernovae and what makes a gamma ray burst? Theorists perhaps in a wind? The material in the disk is hot enough so have speculated that it is the degree of rotation of the pre- that it is dissociated into free neutrons and protons. Not all supernova star. Stars with too much rotation do not collapse the material will be accreted into the black hole, some will and bounce efficiently enough to produce a robust shock. be ejected and the free neutrons and protons will recombine Instead the core collapses into a black hole, surrounded by into nuclei. If the material is sufficiently neutron rich, as an accretion disk. Neutrinos are emitted copiously off of would be the case for very high accretion rates, we may the surface of this disk. Depending on the accretion rate and find the r-process. If the material is roughly 50% neutrons the spin parameter of the black hole, the neutrinos may or and 50% protons, considerable nickel will be produced, but may not be trapped in the inner portion of the disk. In either perhaps also an unusual smattering of other rare nuclei. case, only electron type neutrinos and antineutrinos are produced because the temperatures are lower than they are in Outlook the core of the proto-neutron star in the regular supernova. In summary, the subject of supernovae is a unique combi- The geometry of the disk provides maximum opportunity nation of many different branches of physics, and there are for neutrino-anti-neutrino annihilation. Heating from many different ways in which we can probe their inner work- neutrino-anti-neutrino annihilation, combined with electro- ings. Traditional astronomy uses photons of all wavelengths magnetic extraction of energy from the rotating black hole and spectra can be used to probe nucleosynthesis products. may be responsible for powering the burst. The burst itself We can now supplement this information by measuring neu- consists of ultra-relativistic ejecta emitted directly above trinos from future galactic supernovae. Theoretically there is the black hole. Models for this process are currently being much to learn by combining nuclear reactions, neutrino scat- developed and it will likely prove even more challenging tering, general relativity, and much more. In addition to that than modeling the traditional core collapse supernova envi- we are discovering whole new types of events that are also ronment due to the more complicated geometry and the associated with supernovae. Whatever the future of super- stronger effects of general relativity. nova research brings, it promises to be an exciting time. The neutrinos that are emitted from the disk have average energies on the order of a few MeV. In addition to 15 these, very high-energy neutrinos of around 10 eV can be References Q3 produced by photo-pion reactions. High energy protons can 1. H. A. Bethe, Supernova mechanisms, Rev. Mod. Phys., 62, scatter off the radiation field of the source and produce 801–866 (1990). pions that decay into muons and neutrinos. Because gamma 2. A. Burrows and T. Young, Neutrinos and supernova theory, ray bursts are rare, we are unlikely to observe one in our Phys. Rep., 333, 63–75 (2000). 3. A. I. MacFadyen and S. E. Woosley, Collapsars: Gamma ray Galaxy, but very high-energy neutrinos can be detected bursts and explosions in failed supernovae, Astrophys. J., 524, even if they originate from objects well beyond our Galaxy. 262–269 (1999). It may be possible to observe these neutrinos with kilometer 4. P. Meszaros, Theories of gamma-ray bursts, Ann. Rev. Astr. cubed detectors such as Ice Cube and Amanda. Astroph., 40, 137–169 (2002). This new type of core collapse supernova will produce a 5. E. M. Burbidge, G. R. Burbidge, W. A. Fowler, F. Hoyle, Syn- unique set of nucleosynthesis products. Although these thesis of the elements in stars, Rev. Mod. Phys., 29, 547 events are fairly rare, perhaps 10 −5 per year per galaxy as (1957). opposed to 10 −2 per year per galaxy for typical supernovae, 6. B. S. Meyer, The r-, s-, and p-processes in nucleosynthesis, Ann. Rev. Astr. Astroph., 32, 153–190 (1994). they can still contribute significantly to cosmic element 7. C. Sneden, J. J. Cowan, Genesis of the heaviest elements in abundances. What elements are produced in gamma ray the Milky Way Galaxy, Science, 299, 70 (2003). bursts? It is difficult to know for certain until more com- 8. K. Langanke, G. Martinez-Pinedo, Nuclear weak-interaction plete hydrodynamic models exist. However, some things processes in stars, Rev. Mod. Phys., 75, 819 (2003).

4 Nuclear Physics News, Vol. 15, No. 3, 2005 High-Resolution Gamma-Ray Spectroscopy at TRIUMF-ISAC

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High-Resolution Gamma-Ray Spectroscopy at TRIUMF-ISAC

Introduction cidences to isolate specific decay for near- or above-barrier nuclear It is no accident that the rapid techni- branches from otherwise overwhelm- physics experiments [3]. cal evolution of radioactive beam facili- ing backgrounds. ties has coincided with challenges to the The Tri-University Meson Facil- The 8␲ spectrometer standard models of nuclear structure and ity (TRIUMF) cyclotron can deliver The HPGe detector array now fundamental interactions. In nuclear up to 100 µA 500 MeV proton beam to known as the 8π spectrometer began structure, the shell model is a de facto the Isotope Separator and Accelerator as a joint venture between Université standard model. The properties and sys- (ISAC), a modular high-power ISOL- de Montréal, McMaster University tematics of nuclei near stability are well type radionuclide production and mass and Atomic Energy of Canada Lim- understood in terms of the magic separation system. Activities are ion- ited (AECL). It was named after an nucleon numbers at shell closures. How- ized, extracted, and delivered to the initial conceptual design with a 4π ever, when confronted with experimen- low-energy area for decay experi- inner calorimeter and a 4π suppression tal data on increasingly exotic nuclei, ments, or injected into radio-fre- scheme. The 8π was installed in 1985 the model fails. The near-stability magic quency quadrupole and drift-tube at AECL Chalk River’s Tandem nucleon numbers disappear, and new linear accelerators (DTLs) for delivery Accelerator Superconducting Cyclo- ones emerge [1]. This is evidenced for to higher-energy experimental sta- tron (TASCC) facility, where it was example by the energies and γ transition tions. ISAC-I accelerates ions with used primarily for pioneering work in rates of excited states. These excitations mass-to-charge A/q<30 up to 1.8MeV/ high-spin nuclear structure. In 1997, may be probed by reactions induced u primarily for nuclear astrophysics the 8π moved to Lawrence Berkeley with accelerated radioactive beams, or experiments. When completed in National Laboratory, and in 2000 it by a parent β decay. At the same time, 2007, the charge state booster and was repatriated to the ISAC low- high production yields for selected iso- superconducting DTLs of ISAC-II energy beam area [4]. topes allows for very high precision will deliver beams with masses up to The 8π (Figure 1) has been recon- measurements of specific decay pro- A ~ 150 at energies up to 6.5 MeV/u figured for high-precision β-decay cesses. Because β decay is a nuclear manifestation of the weak interaction, high precision measurements of nuclear β decay provide a strict test of fundamental symmetries [2]. Gamma-ray spectroscopy has long been a cornerstone of decay and in- beam nuclear physics experiments. For these measurements, high-purity germanium (HPGe) detectors deliver the necessary energy resolution and efficiency. Signal-to-noise, that is, peak-to-total ratios, can be further improved by surrounding the HPGe with inorganic-scintillator escape suppression shields that veto events with only partial photon energy deposition. Gamma-ray spectroscopy is most powerful in multi-γ or γ-particle coin- Figure 1. The 8π, downstream half of SCEPTAR, and tape system.

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measurements. The inner calorimeter of 1.0% at 1.332 MeV, and a peak-to- decay curves and measure the 34Ar and front suppressor shields have total ratio of 41% for 60Co. half-life with the necessary precision. been removed, and the 20 HPGe and The upstream 10 detectors of However, 34Ar also emits γ rays fol- bismuth germanate (BGO) suppres- SCEPTAR may be replaced with the lowing the β decay, so γ-ray counting sors have been moved forward. Pentagonal Array Conversion Elec- is promising for measuring the 34Ar Hevimet collimators prevent the tron Spectrometer (PACES), up to half-life with the needed precision. BGO suppressors from viewing γ five cryogenically cooled 5 mm thick The technique has been investigated in rays from the HPGe focus. Delrin Si(Li) detectors subtending 6% solid detail with 26Na decay, to compare tra- absorbers stop β particles from enter- angle (Figure 2) [5]. PACES has ditional β counting with γ counting. ing the HPGe while minimizing recently been used in an in-beam experi- The first measurement in this program bremsstrahlung. ment elucidating low-spin 156Dy struc- has been the half-life of 18Ne, yielding tures populated by 156Ho β decay [6]. a measurement with a statistical Associated Systems uncertainty of ~0.1% [7]. Measure- SCEPTAR, the Scintillating Elec- Science Highlights ments on other superallowed Fermi tron-Positron Tagging Array, consists The High Precision Program: The β-decay nuclei will continue as ISAC of twenty thin plastic scintillators (∆E 8π and its new associated equipment beams become available. 176 of 500 keV for minimum ionizing are intended for high precision Lu: The first measurement with electrons) in vacuum subtending 80% (~0.05%) measurements of lifetimes the 8π at ISAC was the half-life of 176 of the solid angle around the 8π focus and branching ratios in superallowed the geochronometer Lu. By count- (Figure 2). Each HPGe is co-linear to 0+→0+ Fermi β decays [2,4]. These ing γ-γ coincidences with 8π HPGe the focus of the array with a unique measurements test the Conserved detectors, several sources of system- SCEPTAR scintillator. Vector Current hypothesis and the atic uncertainty were eliminated. A 176 The tape system (Figure 1) is a unitarity of the CKM quark-mixing half-life of Lu of 40.3(3) billion continuous loop up to 150 m long matrix. High precision γ and conver- years was reported. [8] moving at up to 1.3 m/s. It is intended sion electron measurements are High-K isomers are a prime exam- to remove long-lived activities (daugh- needed not only for branching ratios, ple of the interplay between collective ters or beam contaminants) out of the but in selected cases, also for measur- and single-particle degrees of freedom focus of the detectors and behind a ing lifetimes. For example, 34Ar and in nuclear systems [9]. The 8π was lead wall. With SCEPTAR, the tape its daughter 34Cl both β decay and first to observe the M4 and E5 γ rays system, and Delrin absorbers installed, have nearly the same half-lives, so it is de-exciting a high-K isomer, namely 178m2 the 8π has a γ-ray photopeak efficiency impossible to disentangle their β the 31-year Hf isomer. These are ~10−4 branches, and establish a reduced hindrance factor of ~100 for all observed K-isomer decay branches of this isomer [10]. The 8π also has been used in a campaign to identify new high-K isomers in ISAC beams [11]. In the first experiment, a new isomer in 174Tm with a half-life of 2.3 s has been identified [12]. The tape system was critical for removing long-lived daughters and beam isobars from the focus of the HPGe detectors. 11Li: The halo nucleus 11Li and its daughter 11Be are classic examples of novel nuclear behavior at the extremes Figure 2. Downstream half of SCEPTAR (left); PACES (right) with three of five of weakly bound nuclei. However, Si (Li) installed. despite numerous experimental studies,

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discrepancies persist in γ ray intensities allowed in the observed β-n-γ cascades. outstanding intensity and feeding dis- following β decay and in the level The data also confirmed the existence of crepancies, with higher statistics, n-γ scheme for neutron-unbound 11Be an 8.03MeV state in 11Be first postu- angular correlation parameters can be states ([13–15] and references therein). lated in Ref. [13]. The data show clear constrained for spin assignments. Also, In one of the first 8π in-beam experi- evidence that the 8.81MeV state decays by vetoing co-linear β-γ coincidences, ments, 500 atoms/s of 11Li were depos- by neutron emission to the 10Be 2− and bremsstrahlung continuum is suppressed; + ited on an aluminum foil at the array 2 2 states, but no evidence for decay to for example, the overall continuum focus. The lineshapes for 10Be γ rays the 1− state. This is consistent with a background near the 219keV 10Be line (Figure 3) are Doppler broadened due to spin and parity of 5/2− for the 8.81MeV is reduced by 40% [16]. the recoil of the residue following 11Be* state in 11Be, raising questions about the neutron emission. These lineshapes structure of this state and the possible TIGRESS depend on the energies, spins, branching halo-neutron survival through a core Accelerated radioactive beams can ratios, and lifetimes of states in the β-n-γ decay process [14]. However, like all be used to access excited states in 11 decay chain. The data were analyzed by previous measurements in Li, discrep- exotic nuclei through mechanisms comparison with Monte-Carlo simula- ancies remain; Fynbo etal [15] did not such as inelastic scattering, particle 11 tions of the decay of Li and of the stop- report any evidence for the 8.03MeV transfer, and fusion-evaporation. Each 10 11 ping of the Be recoil in aluminum. state in Be. The experiment has has its own role for probing collective 10 Lifetimes of states in Be were mea- recently been repeated with the 8π and or single-particle modes over ranges of sured, and limits on n-γ correlation SCEPTAR, generating a data set ~20 excitation energy and angular momen- parameters were consistent with spins times larger. Along with resolving tum. However, experiments with radioactive beams face additional challenges of limited beam intensity, iso- baric contamination, and Doppler shift of γ rays from reaction products. HPGe outer-contact segmentation and digital signal processing provide high effective granularity for measuring the laboratory-frame γ emission angle. The arrays become compact and offer a cost-effective solution for high efficiency without excessive Doppler cor- rection uncertainty. Large arrays of high effective-granularity HPGe detectors have been installed at many of the premier radioactive beam facilities, including CLARION at Oak Ridge, SeGA at Michigan State, Miniball at REX-ISOLDE, and EXOGAM at GANIL [4]. The 8π’s small and unseg- mented HPGe detectors are best suited to their current role in decay spectroscopy. In-beam spectroscopy, with the high-energy, high-mass beams from ISAC-II, requires a new array. The TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer Figure 3. Selected Doppler-broadened γ rays and fits in 11Li β− decay, taken (TIGRESS) will comprise 12 units of from [14]. HPGe four-crystal “clover” detectors,

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efficiency configuration and high peak-to-total configurations. [21].

Summary High energy-resolution γ-ray spectrometry is a powerful and versatile technique in nuclear physics research. At ISAC-I, the 8π and associated tape system, SCEPTAR and PACES have been installed for high-precision β- decay measurements, and have already demonstrated their broad applicability to outstanding nuclear physics questions. The TIGRESS array will provide the high efficiency and high effective granularity needed to meet the challenges of nuclear structure experiments with accelerated radioac- Figure 4. The TIGRESS Concept. 12 unit array, high-efficiency (Hi-ε) tive beams from ISAC-II. configuration; clover HPGe configuration, showing quadrant and lateral segments; suppressors in Hi-ε and high peak-to-total (Hi-P/T) configurations, Acknowledgments identifying back catchers (J), side catchers (K), and front shields (L). Major equipment and operating support for the 8π, SCEPTAR, and TIGRESS is provided by the National (Figure 4), with back and side suppres- rations in one working day with no re- Science and Engineering Research sors mounted to the cryostat. These units cabling or detector removal. First Cou- Council of Canada. The U.S. Depart- are arranged in a rhombicuboctahedral lomb excitation experiments with four ment of Energy has contributed to geometry and can be inserted to a close- units are expected in mid-2006, with PACES, the tape system, and packed configuration for a high photo- completion of the array in 2009 for upgraded 8π electronics. TIGRESS peak efficiency of ~12% for 1MeV pho- fusion-evaporation and particle-transfer prototype detectors were funded tons, or can be withdrawn for insertion reactions in concert with auxiliary through the Canadian Foundation for of front-suppressor BGO plates in a charged particle and recoil detectors. Innovation and Ontario Innovation high-peak-to-total configuration. In both A prototype HPGe detector unit Trust. TRIUMF receives federal fund- cases a spherical volume with a radius was shown to meet expectations. In ing through a contribution agreement of 11cm is available for auxiliary detec- standard tests with 1332 keV gamma with the National Research Council of 60 tors and target chambers. Each of the rays from Co sources, all four AC- Canada. >38% relative efficiency HPGe crystal coupled center contact full-volume outer contacts is segmented eightfold, signals gave better than 2.3 keV energy References into four quadrants and with a lateral resolution, and the efficiency of the 1. H. Grawe, Act. Phys. Pol., B34, 2267 depth segmentation, for sub-segment full unit was 215% in addback mode. (2003). effective granularity through waveform All outer contacts, instrumented with 2. I. S. Towner and J. C. Hardy, J. Phys. analysis. All signals will be digitized room temperature FETs, delivered G, 29, 1997 (2003). with custom-built readout and triggering <3.2 keV resolution [18]. The single- 3. R. E. Laxdal, Nucl. Instr. Meth. Phys. systems developed in parallel with those interaction position sensitivity, as Res. B, 204, 400 (2003). for another major TRIUMF initiative, defined by Vetter et al. [19], is 4. C. E. Svensson et al., Nucl. Inst. Meth. Phys. Res. B, 204, 666 (2003). KOPIO [17]. The support frame will 0.44 mm [20]. A set of prototype sup- 5. E. F. Zganjar, private communication. allow rapid redeployment from the high- pressor shields yielded peak-to-total 6. W. D. Kulp. private communication. efficiency to high-peak-to-total configu- ratios of 35% and 50% in the high- 7. M. B. Smith, private communication.

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8. G. F. Grinyer et al., Phys. Rev. C, 67, 14. F. Sarazin et al., Phys. Rev. C, 70, 20. C. E. Svensson et al., accepted, Nucl. Q2 014302 (2003). 031302(R) (2004). Inst. Meth. Phys. Res. A. 9. P. M. Walker and G. D. Dracoulis, 15. H.O.U. Fynbo et al., Nucl. Phys., 21. M. Schumaker et al., private com- Q3 Nature (London), 399, 35 (1999). A736, 39 (2004). munication. 10. M. B. Smith et al., Phys. Rev. C, 68, 16. C. Mattoon, private communication. 031302(R) (2003). 17. D. Bryman and L. Littenberg, Nucl. GREG HACKMAN 11. M. B. Smith et al., Nucl. Phys. A, 746, Phys. B, 99, 61 (2001). TRIUMF, Vancouver, BC, Canada 617c (2004). 18. H. C. Scraggs et al., submitted to Nucl. Q1 12. R. S. Chakrawarthy et al., ENAM’04 Inst. Meth. Phys. Res. A, and TRIUMF Proceedings, in press (2004). Preprint PP-04–23 13. N. Aoi et al., Nucl. Phys., A616, 181c 19. K. Vetter et al., Nucl. Inst. Meth. Phys. (1997). Res. A, 452, 223 (2000).

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Radioactive Ion Beam Facility in Brazil (RIBRAS)

R. LICHTENTHÄLER, A. LÉPINE-SZILY, V. GUIMARÃES, M.S. HUSSEIN Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo SP

Nuclear physics has been going through a major evolution over the last decade with the possibility of producing secondary beams of nuclei far from the stability line (exotic nuclei). Many new facilities have been put to work in order to investigate nuclei at extreme conditions of density, temperature, and with a high number of protons or neutrons. In particular, the possibility of using exotic nuclear beams has opened an exciting field of investigation in nuclear physics with strong implications in nuclear astrophysics. The Pelletron Laboratory of the University of São Paulo installed the first South American Radioactive Ion Figure 1. RIBRAS Facility installed in the 45B Pelletron beam line (foto beams device (RIBRAS) [1–3]. This Eduardo Cesar). facility extends the capabilities of the original Pelletron accelerator by producing secondary beams of unstable present Pelletron Tandem of 8 MV nique using a pulsed primary beam is nuclei. terminal voltage (3–5 AMeV). also very useful to identify nuclei of A picture of this facility is shown The presence of the two magnets interest in the secondary beam. The in Figure 1. is very important to produce pure sec- buncher system to pulse the primary The most important components in ondary beams. The first solenoid beam of the Pelletron accelerator is this facility are the two new super- makes an in-flight selection of the presently being installed. conducting solenoids. The solenoids reaction products emerging from the An additional future possibility have 6.5T maximum central field primary target at forward angles. As for the two solenoid system is the (5T.m axial field integral) and a 30 cm the first magnet transmits all ions production of tertiary beams using a clear warm bore, which corresponds with the same magnetic rigidity secondary target in the mid scattering to an angular acceptance in the range (Bρ)2 = mE/q2 the purity of the radio- chamber. The second solenoid can be of 15deg ≥ θ≥ 2deg. active secondary beam in the mid- tuned to select a different magnetic The solenoids were manufactured scattering chamber can be rather poor. rigidity producing low intensity (1– by Cryomagnetics INC (USA) and With two solenoids, it is possible to 100/s) tertiary beams like 9Li, 8He were designed to operate in connec- use differential energy loss in a [4,5]. This is, in principle, possible tion with the Linac post-accelerator of degrader foil, located at the crossover with secondary beams of 107 p/s and maximum energy of 10 AMeV, pres- point between the magnets. This assuming a typical conversion effi- ently under construction. With the degrader foil will allow the second ciency of 10 −5 for the secondary LINAC, the energy of the primary solenoid to select the ions of interest reaction. beam will be about 2–3 times larger by moving the contaminant ions out The two solenoids are presently than the maximum energy of the of its bandpass. Time of flight tech- installed in the 45B Pelletron beam

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line. It should be noted that setting up 80% in many cases. In addition, the sten Faraday cup that suppresses the of the double solenoid system prior to pulsed time structure of the beam will primary beam and measures its cur- the completion of the LINAC post- provide a time-of-flight parameter rent. The gas cell was mounted with a accelerator is an important issue. This that can be used to reduce back- 2.2 µm Havar entrance window and a makes possible to begin experiments grounds in many experiments. On a 12 µm thick 9Be vacuum-tight exit with a facility that is similar to the more speculative note, if uranium window, which plays the role of the TWINSOL system at Notre Dame beams could be accelerated to ener- primary target and the window of the University [5]. This first stage with gies of a few MeV per nucleon, trans- gas cell at the same time. The gas the Pelletron primary beam of 7,6Li of fer induced fission reactions could be inside the cell has the double purpose 3–5 AMeV and 1 µAe maximum cur- used to produce a wide variety of very of cooling the Berilium foil heated by rent, allows the production of second- neutron rich fission fragments. The the primary beam and as production ary beams such as 7Be, 8B, 8Li, 6He beams formed in this way are not target. In case we want to use a gas with intensities around 104 to 106 par- likely to be very pure, but they could target to produce secondary beams, ticles per second. With these intensi- be useful in a number of experiments. the Berilium foil can be replaced by ties one can perform measurements of However, this extended project would another Havar foil and the pressure elastic scattering angular distributions require the installation of a low-β ini- inside the cell can be increased up to and studies of the interaction potential tial acceleration stage and an ECR several Bars. of systems involving exotic projec- source at the LINAC. In Table I we present some typi- tiles allowing the investigation of The first radioactive beams from cal production rates and reactions phenomena such as proton and neu- the RIBRAS facility were delivered used at Notre Dame and at RIBRAS, tron halo in nuclei. in February 2004 during the XIII J. A. São Paulo. Probably the most important Swieca Summer School on Experi- The secondary beam profile (x-y) impact of the research with low mental Nuclear Physics. The 8Li and was measured by a Paralell Plate Ava- energy RIB is in nuclear astrophys- 6He particles produced by the reaction lanche Counter (PPAC) placed in the ics. The possibility of measuring the of the 7Li primary beam on the 9Be crossover point. A triple silicon telescope ∆ µ µ µ cross sections of capture reactions of primary target were focused by the ( E(20 m)-E1(150 m)-E2(150 m)) astrophysical interest involving first solenoid in the scattering cham- placed at zero degrees and a few centi- exotic nuclei will certainly have ber located at the crossover point meters beyond the PPAC allowed the important consequences in the mod- between the two solenoids. Only the identification of the atomic number, els of the primordial as well as in the first solenoid was used in this first mass and the energy of the secondary explosive nucleosynthesis. The pri- test. beam particles. Figure 2 shows the mordial nucleosynthesis involves The production system (primary PPAC x-y spectrum obtained with the reactions with light nuclei that target) consists of a gas cell, mounted 8Li secondary beam produced by the would be accessible with RIBRAS in a ISO chamber followed by a tung- reaction 9Be(7Li,8Li). beams. In the inhomogeneous model of the primordial nucleosynthesis there are new paths near the neutron drip line involving nuclei like 8Li, Table 1. 6 He that would lead to the synthesis Production reaction secondary beam (part/s/ؔAmp of 11B [6]. The RIBRAS facility will have 9Be(7Li,8Li) (*) 106 several important up-grades provided 9Be(7Li,6He) (*) 105 by the linear post-accelerator 3 7} 7 (*) 5 (LINAC). In particular, radioactive He( Li, Be) 10 ion beams with higher energy (up to 3He(6Li, n)8B 105 10 MeV/nucleon) and higher mass 12C(17O,18mF) 103 (perhaps up to A = 50) can be produced with beam purities approaching (*)Production reactions measured at RIBRAS using only 1 solenoid.

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in the crossover point. The operation of the second solenoid depends on the installation of the secondary scattering chamber that is under construction. In conclusion, a double superconducting 6.5T (5T.m) solenoid system is installed at the Pelletron Laboratory of the University of São Paulo to produce secondary beams of radioactive nuclei. The two solenoids were mounted and tested on the 45B beam line of the Pelletron experimental area. The system began its operation using only the first solenoid and the 7Li primary beam of the 8MV Pelletron Tandem. Secondary beams of 8Li,7Be and 6He were produced. Experiments using these secondary beams are in progress.

References 1. Progress in RIBRAS Radioactive Ion Beams in Brasil Project, R. Lichtenthäler, A. Lépine-Szily, V. Guimarães, G. F. Lima, M. S. Hussein, Nuclear Inst. and Figure 2. X-Y Position spectrum (PPAC) of the 8Li secondary beam. Methods, A505 (2003) 612–615c. 2. Radioactive Ion Beams in Brasil (RIBRAS), R. Lichtenthäler, A. Lépine- The secondary beam spot measured at the PPAC position was about 7 mm in diameter which is consistent with a primary beam spot size of 4–5 mm multiplied by a mag- nifying factor of 1.5 of the first solenoid. Figure 3 shows the ∆E-E telescope spectra with the solenoid tuned to select 8Li and 6He ions respectively. The production rates measured at RIBRAS for these two exotic ions were of 104 p/s and 105 p/s respectively with a 300 nAe of primary beam. One can observe the presence of contaminants in the secondary beam like 7Li2+ degraded primary beam and light particles. These Figure 3. Left panel: E-∆E spectrum of the 8Li secondary beam produced by the contaminants can be eliminated by 9Be(7Li,8Li)8Be reaction.Right panel: E-∆E spectrum of the 6He secondary beam the second solenoid using a degrader produced by the 9Be(7Li,6He)10B reaction.

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Szily, V. Guimarães, G. F. Lima, M. S. Kolata, V. Guimarães, D. Peterson, 6. P. D. Zecher, A. Galonsky, S. J. Hussein, Brazilian Journal of Physics, P. Santi, Nucl. Instrum. and Methods in Gaff, J. J. Kruse, G. Kunde, E. 33, no.2 (2003)294. Phys. Res., A422 (1999)505. Tryggestad, J. Wang, R. E. Warner, 3. Ribras: Radioactive Ion Beams in Brasil, 5. A radioactive beam facility using a D. J. Morrissey, K. Ieki, Y. Iwata, F. M. S. Hussein, Nuclear Physics News, large superconducting solenoid, J. J. Deák, Á. Horváth, A. Kiss, Z. Seres, 9 (1999) 28. Kolata, F. D. Becchetti, W. Z. Liu, D. J. J. Kolata, J. von Schwarzenberg, 4. F. D. Bechetti, M. Y. Lee, T. W. O’Donnell, A. Roberts and J. W. Janecke, Nucl. H. Schelin, Phys. Rev., C57 (1998) D. A. Roberts, J. A. Zimmerman, J. J. Instrum. Meth., B40/41(1989) 503. 959.

4 Nuclear Physics News, Vol. 15, No. 3, 2005 BEN@ECT*: The New 1Tflop/s Computing Facility at The European Centre for Theoretical Studies in Nuclear Physics and Related Areas

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BEN@ECT*: The New 1Tflop/s Computing Facility at The European Centre for Theoretical Studies in Nuclear Physics and Related Areas

Introduction reflect the relationship between adjacent that are of significant interest for the One current trend in most branches nodes. Although many computationally scientific community: of contemporary research is the adop- hard scientific problems are naturally tion of large computing facilities, capa- mapped on such a computational model, 1. To develop a novel network tech- ble of calculating models of ever most off-the-shelf networking products nology, capable of overcoming the increasing complexity. This is particu- are modeled on a switched architecture limitation of the traditional larly true for Nuclear Physics, a disci- that might not streamline the actual flow approaches; pline that has often prompted the of information. 2. To provide a computing resource development of new theoretical and The technology developed by the adequate for the most advanced numerical methods that stimulated the partners of the initiative and imple- projects; advance of computing machinery. mented at the computing facility 3. To allow and promote the sharing The need for better computational allows for a different approach at clus- of knowledge between a distrib- hardware was recognized by the ECT* tered networking that employs a uted base of users, with particular Board in 2003, with the decision to switchless, hardwired 3-D communi- attention for young researchers; start a joint program between the Isti- cation mesh. 4. and, therefore, to qualify for tuto Nazionale di Fisica Nucleare The deployment of the 1Tflop/s com- becoming a “GRID” node. (INFN) [1], the Istituto Trentino di Cul- puting facility is at an advanced stage: the tura (ITC) [2], the Provincia Autonoma cluster is already in production, with stan- The primary goal of this installa- di Trento (PAT) [3], and Exadron [4], dard networking; the boards and software tion is to foster projects that are the High Performance Computing layer for the new inter-node connectivity aligned with ECT* scientific activi- Division of the Eurotech [5] group. technology are under production and will ties; however, it is open to projects The result of the cooperation is an be installed shortly. and initiatives belonging to different advanced computing infrastructure, cen- Finally, it should be remarked that domains. tered on a 1TFlop/s cluster and an inno- the ultimate goal of the project is to The other ambitious goal that was vative networking technology, especially bring the capabilities of the new facil- set is the attempt to demonstrate that it is suited for the exacting needs of a distrib- ity to a large number of users: soon possible to overcome the many obsta- uted community of researchers. after the public opening of the system, cles that often separate Theoretical Sci- One important aspect of the ECT* a Call for Proposals will addressed to ence and Engineering. In fact, most of installation is the development of a a broad spectrum of scientists. This the traditional networking technologies pioneering network technology that initial phase is expected to evolve nat- used in high-performance computers aims at improving the current state of urally toward the participation to a were not designed having in mind the the art in clustered computing. In fact, “GRID,” or “GRID-like” environment special needs of scientific computing. although–numerous commercial prod- that could allow the sharing of compu- For this reason, ECT* decided to ucts are already available (Infiniband, tational power among an enlarged become the test-bed for a novel device Myrinet, Quadrics, etc.), their general community of researchers both from that has been developed by the APE purpose design does not necessarily fit Academia and Industry. group of INFN and Exadron. optimally with the technical require- This new hardware derives from a ments for scientific computing. 10-year-long experience in the APE It is well known that lattice or mesh Priorities project [6,7], one of the most success- computing have very specific data The computing facility stems from ful European initiatives for the cre- access and transmission patterns that the need to fulfil a set of requirements ation of a series of massively parallel

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System Description (preliminary drivers). This figure The current implementation of the includes the PCI bus latency; this facility revolves around the cluster means that the actual fabric latency is architecture. The following tables sum- negligible. The device is characterized marize the main technical features: by three major functional blocks: Q1 The system is currently running Fedora Core 2 [9], integrated with many • The PCI-X interface. clustering tools. Although many inter- • The embedded crossbar switch. esting solutions for clustering exist • The communication links. (Rocks [10], Oscar [11], etc.) it was preferred to use a stable, yet up-to-date Each board is connected to the 6 distribution upon which the necessary neighboring nodes via differential infrastructure could be deployed, links, therefore implementing a 3-D therefore allowing for a better control mesh of links. According to this over the interaction of the different scheme, it is possible to establish a components. direct transmission with those nodes Due to its experimental nature, it that are actually interested in most of is possible that the overall configura- Figure 1. One example of the three the communications occurring in a lat- tion of the system might change over cabinets composing the ECT* cluster. tice/mesh calculation. The packets time, in order to adapt to the evolu- The computational units are encased directed to other nodes are routed, tion of the networking technology. in a very compact blade format (up to thanks to the embedded crossbar From the user’s point of view, the 20 CPUs in 3U). switch that relays them, to the next system provides a rich set of facilities board. The cost of traversing a large that include: mesh side-to-side is negligible and amounts to few clock cycles per node supercomputers dedicated to lattice • GNU [12] and other Open Source traversed (nanoseconds). Therefore, it computing. In particular, one peculiar compilers for the most common aspect of the APE supercomputer is languages (FORTRAN, C, C++, how the inter-node communication is JAVA, etc.). Table 1. Overall features. implemented [8]. Now, a technology • Scientific and general libraries (MPI based on the experience drawn from [13,14], ATLAS [15], BLAS [16], Computing nodes 96 the APE project is going to be installed CERNLIB [17], FFTW [18], etc.). File server nodes 3 in the ECT* machine. This will allow a • Job scheduling and administration Master node 1 superior performance in calculations tools (Torque [19], Maui [20]). where intense neighboring node com- • Hardware status monitoring (Gan- Total peak 1.1 TFlop/s performance (RPeak) munication is requested, besides being glia [21]). very competitive in general. • A number of applications on Expected performance 0.6 TFlop/s In this respect, a future, possible request by the users. (RMax) (Gbit eth) participation to a “GRID” is per se an Expected performance ~0.8 TFlop/s important challenge: the open nature 3-D Network Technology (RMax) (APE tech) of this kind of infrastructure will, at The novel 3-D inter-node connec- Total RAM capacity 100 GByte least in principle, allow the interaction tivity technology developed by the ini- Total Disk capacity 4 TB (internal) + 4.8 TB and cooperation of many different tiative consists in a PCI-X board (external arrays) kind of entities. Therefore, it is funda- compatible with any standard server Inter-node network 2 independent networks mental to establish a solid, yet flexible that provides 6 full-duplex channels. (Gigabit Eth) (MPI and filesystem) framework, capable of allocating the Each channel has a nominal speed of diverse needs of a multifaceted com- 6.4 Gb/s for each direction with an Inter-node network 6-neighbor flexible (APE tech) topology munity. overall estimated latency of 6.3 µs

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Table 2. Computing node features. standard parallel codes on the system. ation: in particular, both theoretical While not yet complete, a subset of and applied proposals for GRID-related CPUs 2 × Xeon @2.80 GHz the functions provided by MPI is and/or interdisciplinary work will be RAM 1 GB available: for instance, it is possible to welcome. compile and run codes such as the Local Disk capacity 40 GB HPL22 benchmark. Network interfaces 2 × Gigabit eth + 1 × APE Industrial Partnership tech (6 channel) It is worth mentioning the active Projects and Opportunities role that Exadron, one of the few Whereas a number of internal supercomputer manufacturers in is possible to effectively build a projects are emerging, external proposal Europe, is having in this project. In switchless infrastructure (i.e., with- are most welcome and will be evaluated fact, Exadron has devoted a signifi- out a central switch or a tree of by an ad hoc commission as soon as the cant amount of internal resources to switches) that is highly optimized cluster has been opened to the public. the development of the cluster facility. toward patterns of traffic that exhibit For this reason, ECT* will stimu- Whereas most cluster installations heavy local communications, with- late the participation to its high- use commodity hardware that has not out having to pay a penalty for non- performance computing initiative with been designed for scientific applica- local transmission. a Call for Proposals addressed to a tions, Exadron has developed a num- Specific drivers have been devel- broad spectrum of scientists. Although ber of crucial components specifically oped for the Linux kernel: both 2.4 the main focus of the Centre is for the needs of the research community. and 2.6 kernel series are supported. Nuclear Physics and related areas, any Moreover, Exadron is the indus- The MPI libraries are being recoded in innovative and computationally demand- trial partner of the APE group, another order to allow a smooth execution of ing project will be accepted for evalu- key player of the project.

Figure 2. Clockwise: the functional blocks of the inter-node communication board; one production board; a “naked” prototype board.

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References 1. Istituto Nazionale di Fisica Nucleare (INFN) – http://www.infn.it/ 2. Istituto Trentino di Cultura (ITC) – http://www.itc.it/ 3. Provincia Autonoma di Trento (PAT) – http://www.consiglio. provincia.tn.it/ 4. Exadron, the HPC Division of the Eurotech Group – http://www.exadron.com 5. http://www.eurotech.it 6. http://apegate.roma1.infn.it/APE/ ape_main.html 7. http://www-zeuthen.desy.de/ape/html/ 8. http://www-zeuthen.desy.de/ape/html/ APEmille/Topology.php 9. Fedora Project—http://fedora.redhat. com 10. http://www.rocksclusters.org/ 11. http://oscar.openclustergroup.org/ 12. GNU Free Software Foundation— http://www.gnu.org 13. http://www-unix.mcs.anl.gov/mpi/ 14. http://www.lam-mpi.org/ 15. http://math-atlas.sourceforge.net/ 16. http://www.netlib.org/blas/ Figure 3. 3-D hardware mesh (only part shown for clarity). Each circle 17. http://cernlib.web.cern.ch/cernlib/ represents a computational unit. Each “tower” is a cabinet with 32 18. http://www.fftw.org/ computational nodes. Extremities are connected together with wrap-around 19. http://supercluster.org/torque/ links (not shown). 20. http://www.clusterresources.com/ products/maui/ 21. http://ganglia.sourceforge.net/ 22. http://www.netlib.org/benchmark/hpl/ The fruitful cooperation estab- Technology Transfer is a real opportu- lished with the ECT* High Perfor- nity even for a centre mainly focused PIERFRANCESCO ZUCCATO Q2 mance initiative is going to have a on theoretical studies, as ECT* is. ECT* PostDoc, Italy pivotal role in the development of an The ECT* computing facility has entire family of high performance been named Ben in honor of Prof. Ben products, therefore demonstrating that Mottelson, the first director of the Centre.

4 Nuclear Physics News, Vol. 15, No. 3, 2005 Recent Achievements in Multinucleon Transfer Reaction Studies at LNL

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Recent Achievements in Multinucleon Transfer Reaction Studies at LNL

Introduction have been implemented [8,9] that are performed within the semiclassical What makes the field of nuclear able to treat quasi-elastic and deep- Complex WKB (CWKB) model (see reactions with heavy-ions so rich is the inelastic processes in terms of few and Ref. [7] and references therein for fact that the nucleus presents both the well-known degrees of freedom and that details). degrees of freedom associated with allow a quantitative comparison with the The experimental data show, for the single particle motion and those experimental observables. neutrons, a quite regular drop of the associated with the strong surface Multinucleon transfer reactions cross-sections as a function of the vibrations and rotations. In the low constitute also a valuable tool to popu- number of transferred nucleons, indi- energy regime (close to the Coulomb late neutron-rich isotopes, at least in cating that the transfer mechanism is barrier) it is the interplay of these two specific mass regions [10]. The study likely to proceed as a sequence of kinds of degrees of freedom that gov- of the lowest excited levels of neu- independent single-particle modes. erns the evolution of the reaction from tron-rich nuclei is an area of increas- Similar results have been obtained at the quasi-elastic to the more complex ing interest for the verification of the Argonne [13]. With the dotted line in deep-inelastic and fusion regimes. The predicted changes of the shell struc- Figure 1 we show the calculations quasi-elastic reactions, where few ture and of the nucleon-nucleon corre- made treating the transfer in a succes- quanta are exhanged between target lations far from the β-stability valley. sive approximation and considering and projectile, constitue the most A very powerful technique for these all the transitions as independent. A important tools for nuclear structure studies is constituted by the coupling good agreement with the data is and reaction dynamics studies [1]. of large gamma arrays detectors with obtained for all pure neutrons transfer From the stripping and pick-up of neu- the new generation of large solid angle channels and for the stripping of one trons and protons one can deduce spectrometers. At LNL the PRISMA proton. However the calculation misses informations about the shell structure heavy-ion magnetic spectrometer [11] the massive proton transfer channels close to the Fermi surface (one-parti- coupled to CLARA [12] recently underpredicting the two-proton strip- cle transfer) of the two reactants or entered into operation. ping by an order of magnitude. The one can study nuclear correlations in discrepancies indicate that the theory the nuclear medium (multi-nucleon Results from Inclusive should incorporate more complex transfer reactions) [2–4]. Among these Measurements with PISOLO transfer degrees of freedom. By add- correlations of particular importance From the comparison between one ing to the reaction mechanism the are the pairing one, that is, the ability and two particle transfer processes one transfer of correlated pairs of protons of two nucleons to form a pair with can already learn a lot on the interplay and neutrons, in the macroscopic zero angular momentum [1,2]. between single-nucleon and pair- approximation, and fixing the strength Extensive work using different transfer modes, but it is only when of the formfactors to reproduce the heavy ion reactions has been performed several number of nucleons are trans- pure −2p channel, one sees (dashed during last few years with the time-of- ferred that one has a better view on line) that the predictions for all other flight magnetic spectrometer PISOLO, how the mechanism evolves. An charge transfer channels are much installed at the Laboratori Nazionali di example of a complete measurement better whereas no appreciable modifi- Legnaro (LNL) [5]. The variety of chan- performed with PISOLO is that for the cations are visible for the neutron nels that could be observed in several 58Ni + 208Pb system [7]. The experi- transfer channels (dotted and dashed experiments allowed to follow in a mental total angle and Q-value inte- lines almost overlap with the full line systematic way the population pat- grated cross-sections for pure neutron in the right panel and are not shown). tern of the reaction products in the pick-up and pure proton stripping Because the pairing interaction has the Z-A plane [6,7]. Parallel to this exp- channels are reported in Figure 1 in same strength for neutrons and pro- erimental work, semi-classical models comparison with the calculations tons we kept the same form factors for

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the +2n and −2p channels. The contri- measured [6] at three bombarding width that increases with the number bution of the pair mode for neutron is energies, for an angle close to the of transferred particles in particular in negligible due to the fact that its effect grazing one. the forward direction. is masked by the successive mecha- Figure 2 shows that only the +1n These observations, both in the nism; notice, in fact, that the cross- and +2n channels have the main popu- TKEL and angular distributions, indi- section for the +1n channel is almost a lation concentrated in a narrow low cate the relevance of the surface factor ten larger than the one of −1p energy region (close to the ground- degrees of freedom. It is, in fact, the channel. In multi-nucleon transfer chan- ground state transition), and the theory surface dynamics, governed by the nels large energy losses are reached, gives a very good description, whereas low lying modes, that allows the two therefore the final yield can be consid- for more massive transfer channels the ions to stay in close contact for longer erably altered by evaporation, mostly populations widen and shift toward times and thus to build up a “neck” neutrons. Including these evaporation more negative Q-values developing between the two colliding partners. effects a much better prediction is tails that increase with the number of Quite interesting expectations are obtained for the final cross-sections, transferred neutrons. This may indi- coming by looking at the Q-value dis- as shown by the full line in Figure 1. cate that, even for this system where tributions of the 40Ca+ 208Pb reaction The calculation includes the transi- all neutron transfer pick-up channels [14]. Figure 3 shows the TKEL distri- tions among all the single particle lev- are at optimun Q-value, the “cold” butions at three bombarding energies els of target and projectile of a full transfers (associated with low excita- for the two-neutron pick-up channel in shell below the Fermi surface and of tion energy) are hindered by processes comparison with CWKB calculations. all the ones above. To see if this that drive the population toward high As can be appreciated, the two neutron choice of the shell model space is excitation energy. By looking at the pick-up channel displays at all measured adeguate for these reactions we look at angular distributions of the same energies a well defined maximum, the Total Kinetic Energy Loss (TKEL) channels one sees that they display a which, within the energy resolution of spectra. In Figure 2 are shown TKEL bell-shaped form (underlying the graz- the experiment, is consistent with a distributions for the system 62Ni + 206Pb, ing character of the reaction) with a dominant population, not of the ground state of 42Ca, but of states with an excitation energy at around 6MeV. From the theoretical calculations one can see how the different single particle levels are populated in the reaction. The inspection of this population for the +2n channel tells us that the maximum of the distributions correspond to the

transfer of two neutrons in the p3/2 orbital; note that the single particle

form-factors for the p3/2 orbital are much larger than the one for the f7/2 orbital that constitutes the main configuration of the ground state of 42Ca. The 2 (p3/2) configuration corresponds to the main component of the excited 0+ states at around 5.4MeV of excitation energy that were interpreted as multi (additional and removal) pair-phonon states [2]. These results open, at least in Figure 1. Total cross-sections for pure proton stripping (left side) and pure our expectation, the possibility to study neutron pick-up (right side) channels for the indicated reaction. The lines are multipair-phonon excitations. The strong the CWKB calculation. concentration of strength near 6MeV

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important to distinguish the population to specific nuclear states and to determine both their strength distribution and decay pattern. This, in fact, carries information on the wavefunctions of the populated levels and on the pairing correlation [1]. Experiments in this direction must exploit the full capability of spectrometers with solid angles much larger than the conventional ones, and with A, Z, and energy res- olutions sufficient to deal also with heavy mass ions. This is now possible with the PRISMA spectrometer [11] designed for the A = 100– 200, E = 5–10 MeV/amu heavy-ion beams of the accelerator complex of LNL. First experiments on heavy- ions grazing collisions have been already performed with beams in the A = 40–90 range. One of the present interests are nuclear structure studies of neutron-rich nuclei, populated at relatively high angular momentum, by means of binary reactions. These studies are performed by combining PRISMA with the CLARA gamma-array [12], recently installed close to the target point and consisting of an array of 24 Clover detectors from the Euroball collaboration. With stable beams and at the energies and intensities typical of tandem accelera- Figure 2. Experimental (histograms) and theoretical (lines) total kinetic energy tors, one can presently reach regions loss (TKEL) distributions for pure neutron pick-up and proton stripping moderately far from β-stability (on channels in the reaction 62Ni + 206Pb. The ground-ground state Q-values are average 3–5 nucleons from the last indicated by the down arrows (see Ref. [6] for details). stable isotope), but one can investigate nuclei through the entire nuclear chart, provided suitable projectile/targets are chosen. of peculiar 0+ states for 42Ca (they must Measurements with the PRISMA An exploratory run with 2 + contain the (p3/2) configuration) is Large Solid Angle Spectrometer PRISMA CLARA has been very clearly visible in the bottom part of Fig- From the discussion in the last recently done by using the reaction ure 3, where the strength distribution section it is clear that for the defi- 90Zr + 208Pb with the main aim of look- S(E) coming from large scale shell nite assigment of the states at ing at the yield production of specific model calculations is shown [14]. around 6 MeV in 42Ca it would be Q-value ranges in the Zr and Sr

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One observes different relative yields the following people: S. Beghini, in mass spectra for each isotope, due E. Fioretto, A. Gadea, G. Montagnoli, to the different gamma multiplicities F. Scarlassara, A. M. Stefanini, for the various multinucleon transfer S. Szilner, M. Trotta. The third sec- channels populated in the reaction. In tion involves the whole PRISMA- the bottom part is shown, as an exam- CLARA collaboration. ple, the coincident gamma spectrum for 90Zr, obtained after Doppler cor- rection for the projectile-like nuclei References Q1 selected by the spectrometer. In gen- 1. A. Bohr and B. Mottelson, Nuclear Structure, Vol. I, edited by W. A. eral, the Zr isotopes span a range from Benjamin, Inc., New York (1969). spherical to highly deformed shapes 2. R. A. Broglia, O. Hansen, and C. Riedel, and it would be therefore interesting Advances in Nuclear Physics, edited to investigate in detail the change of by M. Baranger and E. Vogt, Plenum, the population strength and decay pat- New York, 1973, Vol. 6, p.287. tern properties of specific levels pop- 3. C. Y. Wu, W. von Oertzen, D. Cline, ulated via multinucleon transfer and M. Guidry, Annu. Rev. Nucl. Part. Sci. 40, (1990) 285. mechanism. 4. K. E. Rehm, Annu. Rev. Nucl. Part. Sci. 41, (1991) 429. 5. G. Montagnoli et al., Nucl. Instr. and Acknowledgments Meth. in Phys. Res. A454, (2000) 306. In this report we have presented 6. L. Corradi etal., Phys. Rev. C63, (2001) the results of the collaboration with 021601R.

Figure 3. Experimental (histograms) and theoretical (curves) total kinetic energy loss distributions of the two neutron pick-up channels at the indicated energies. The arrows correspond to the energies of 0+ states in 42Ca with an excitation energy lower than 7 MeV. Bottom panel shows the strength function S(E) from shell model calculations (see Ref. [14] for details).

isotopes close to the expected region where pair vibrational modes may be excited. The spectrum in Figure 4 shows an example of the obtained mass resolution in such a reaction at = Elab 560 MeV. One observes events corresponding to the pick-up as well Figure 4. Panels (a) and (b) : mass distributions for Zr isotopes obtained in the 90 + 208 = θ = 0 as stripping of neutrons. The right side Zr Pb reaction at Elab 560 MeV and at lab 54 , without (a) and with (b) (left side) are the spectra obtained gamma coincidences. Panel (c): single gamma spectrum of 90Zr. The peak at with (without) gamma coincidences. 2186 keV corresponds to the lowest 2+ – 0+ transition.

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7. L. Corradi et al., Phys. Rev. C66, (2002) 024606. 8. A. Winther, Nucl. Phys. A572, (1994) 191; Nucl. Phys. A594, (1995) 203. 9. G. Pollarolo and A. Winther, Phys. Rev. C62, (2000) 054611. Q2 10. The EURISOL Report, Key experiment task group, J. Cornell, ed., GANIL, Dec. 2003; http:/ / www.ganil.fr/eurisol. 11. A. M. Stefanini et al., Proposta di esperimento PRISMA, LNL- INFN (Rep)—120/97 (1997); A. M. Stefanini et al., Nucl. Phys. A701, L. Corradi (left) and G. Pollarolo (right). (2002) 217c. 12. A. Gadea et al., Eur. Phys. J. A20, (2004) 193. 13. C. L. Jiang et al., Phys. Rev. C57, LORENZO CORRADI GIOVANNI POLLAROLO (1998) 2393. INFN-Laboratori Nazionali Dip. di Fisica Teorica 14. S. Szilner et al., Eur. Phys. J. A21, di Legnaro dell’Universita’ and INFN (2004) 87. Legnaro (Padova), Italy Torino, Italy

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Atomic Nuclei at the Extreme Values of Temperature, Spin, and Isospin, XXXIX Zakopane School of Physics, 31 August–5 September 2004, Zakopane, Poland

In 2004 the XXXIX Zakopane and for the organization in general the (presented by W. Meczynski and P. School of Physics (31 August–5 Zakopane School has been always Fallon), of the superdeformed triaxial- September, http://chall.ifj.edu.pl/~maj/ very well recognized by the interna- ity and wobbling motion (presented by Zakopane2004/) was organized by tional community. This is testified to G. Hagemann). In addition interesting Adam Maj from the Instytut Fizyki by the fact that several participants in results were obtained for high-K struc- Jadrowej PAN in Krakow as a five this meeting have also attended many tures at extreme conditions (presented day International Symposium. The of the others of this series in the past. by P. Walker), research of interest also program was concentrated on the The symposium was opened the with radioactive beams. The progress nuclear structure problems in nuclei at first evening by A. Budzanowski made in the understanding of the struc- extreme values of temperature, spin, (director of IFJ PAN Krakow) with a ture of shell-stabilized highly rotating and isospin. The meeting was also lecture on phase transitions in highly heavy nuclei has been discussed by intended to celebrate, on the occasion excited nuclei reviewing the different T.L. Khoo while that chirality in rota- of his 60th birthday, the remarkable experimental signatures pointing to tion was presented by J. Srebrny. Par- achievements of Rafal Broda, a pio- the observation of the liquid-gas ticularly interesting has been the neer in study of neutron rich nuclei phase transition of expanding nuclear discussion on the search of hyperde- with gamma spectroscopy from deep matter. formed configurations that was trig- inelastic collisions. In the following four days the gered by the theoretical talk of J. The meeting gathered 120 partici- symposium was chaired by four con- Dudek and by the experimental talks pants from 15 countries to discuss in a veners, Bent Herskind for the nuclei at of H. Huebel and Nyako illustrating very relaxed and excellent atmosphere highest spin, myself for nuclei at high the different results from several the state of the art of the nuclear struc- temperatures, Hans-Juergen Woller- experiments. The problem of hyperde- ture research and the projects under- sheim for exotic nuclei investigated formation is still open and we can say way for future activities. Whereas the with radioactive beams, and Bogdan that we are in a situation similar to overviews of the different topics in the Fornal for neutron-rich nuclei studied that we had at the beginning of the field were given by the invited lec- with stable beams. 1980s for the problem of superdefor- tures and seminars, the selected The program of the session on mation, namely some signals from the shorter contributions complemented nuclei at the highest spins was mainly quasi continuum are present whereas very well the discussion started by the concentrated on the impressive results the indications from discrete lines are longer talks. It is important to stress obtained with the large arrays Euroball very weak. Therefore it is clear to the that several presentations were given and Gammasphere. It is important to community that it is important to pur- by bright young researchers and grad- stress that these arrays were designed sue this research in the future with uate students demonstrating very high and constructed after the first and very more efficient and selective arrays like capabilities from which the commu- successful activity in the field of high AGATA and GRETA. The status of nity will surely benefit for present and spins led by Frank Stephens, Bent these new arrays, designed and sup- future projects. In addition, physicists Herskind, and Peter Twin—the last ported first by the European and sec- could discuss together more infor- two awarded this year with the Lise ond by the American scientists, has mally in the afternoons either by Meitner prize for nuclear science. The been presented by J. Simpson. strolling around or by taking part in highlight on the key question of The session on nuclei at high tem- the organized hiking excursions on the extreme deformations are the new perature focused on the study of high- very panoramic trails in the moun- findings of very large deformations in lying collective modes built on both tains. Both for high scientific quality the light and medium mass nuclei the ground state and on hot rotating

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nuclei. The overview of the work on opened by T. Otsuka illustrating the shell model in this mass region is also the electric dipole strength below the new shell model predictions on the being made. giant dipole resonance, based on the evolution of shell and collective struc- The session on the neutron rich extensive work made at the University tures in exotic nuclei. His results well nuclei investigated with stable beams of Darmstadt, was given by J. Enders describe the latest experiments at the was dedicated to Rafal Broda. This who pointed the interest in this topic RIB facilities and represent a useful session was particularly lively and in connection with neutron rich nuclei guide for the future experimental pro- the lecturers (P. Daly, S. Lunardi, formed at the radioactive beam facili- grams. The status of the RISING facil- P. Regan, R. Janssens) made an excel- ties. The status on the problem of the ity at GSI has been presented giving lent job in recalling how the technique nuclear compressibility as obtained by both technical details (P. Bednarczyk) based on deep inelastic collision was the isoscalar monopole and dipole and the preliminary results of the first introduced by Rafal and how it then giant resonances has been presented experiments (P. Reiter). These experi- evolved with time. P. Daly pointed out by Y. Lui whereas new results on ments concern the measurements of that “scavenging pays” because in this spin-isospin giant resonances were the B(E2) with Coulomb excitation way Broda and Fornal obtained very illustrated by A. Krasznohorkay. The and the study of isospin mixing in successful results. Nuclear structure future perspectives are related to the mirror nuclei using second fragmenta- programs using deep inelastic reac- activity with radioactive beams and tion reactions. Similar and comple- tions have been carried out in different in particular at GSI a construction of mentary activity on nuclear structure laboratories with the Gasp, Euroball, a dedicated set up with a gas jet tar- with fast exotic beams at lower ener- and Gammasphere arrays and many get is in progress (R3B and EXEL gies is carried out at MSU and the results obtained in different mass projects). main results were presented by regions as those on 68Ni and 50Ca (pre- The new achievements in the field A. Gade. The latest achievements con- sented by R. Broda) are at the basis of of nuclear structure at finite tempera- cern nuclei in the vicinity of the the current work with radioactive ture have been discussed in connec- N = Z = 28 nucleus 56Ni a benchmark beams. The present and near future tion with two different aspects. The for the study of nuclear shells. A experiments are searching for more first concerns the rotational damping wealth of information on heavy neu- exotic nuclei and for short lived states and selection rules in the order to chaos tron rich nuclei characterized by the at higher spin and they are carried out transitions (S. Leoni) whereas the sec- presence of several isomeric states has at the PRISMA-CLARA set up at ond concerns the gamma-decay of been obtained with decay studies with LNL and at Argonne with Gammas- the giant dipole resonance in excited stopped relativistic radioactive beams phere equipped with the Chico particle nuclei (F. Camera, M. Kicinska-Habior, (Z. Podolyak). This research will be detector. F. Gramegna, and M. Kmiecik). Recent followed using the RISING set up The overview of the study of octu- data on the giant dipole resonance in focusing also on the interesting prob- pole deformations, of the rotating excited nuclei have provided a better lem of the shape coexistence. On the heavy nuclei as, for example, Nobe- understanding of the damping mecha- same topic of the shape coexistence lium and in general all the challenges nisms at finite temperature and of the was the presentation of A. Goergen for studying needles in a haystack were isospin mixing. who reported on new investigations at presented by P. Butler. He also pointed In particular, the role of nuclear GANIL on Krypton isotopes. The out the importance for second-genera- deformation in the dipole response at activity carried out at Oak Ridge with tion radioactive beams of ISOL type as very high spins close to the fission limit radioactive beams of ISOL type with SPES at LNL, ISOLDE at CERN, has been investigated with Euroball few MeV/u has been presented by SPIRAL2 at GANIL, and the European experiments. New indications of the R. Grzywacz and K. Rykaczewski. They EURISOL project. These projects are occurrence of the Jacobi shape transition focused on Coulomb excitation mea- all related to high-intensity beams. (oblate–prolate) were found, transition surements of “pure” beams of fission Beam of higher intensities are neces- that is also typical of gravitational fragments such as the semimagic 82Ge sary also in the case of stable beams as objects rotating synchronously. and doubly magic 132Sn, sub barrier it was discussed by F. Azaiez in order The session on exotic nuclei stud- fusion and proton decay. Progress in the to make a substantial progress in the ied with radioactive beams was calculation techniques (K. Pomorski) on search of hyperdeformation, in the

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study of spinning very heavy nuclei on the current status of two-proton After such a successful symposium I and of nuclei around 100Sn. emission. have only two closing remarks: thanks The symposium also included A March 2005 issue of Acta Physica to Adam Maj for his excellent work and another event, namely the Ceremony Polonica B with the proceedings of happy birthday to Rafal Broda! of awarding the Diploma of the 2003 the conference is in preparation. The Zdzislaw Szymanski Prize to Marek next Zakopane School of Physics is ANGELA BRACCO Pfutzner who gave a very good lecture planned for September 2006. Universita’ di Milano and INFN Symposium on “Atomic High-Precision Mass Spectrometry”

Like only a few other parameters German Physical Society. Eight dis- Although the systematic survey of all the mass is a characteristic nuclear tinguished international speakers from available data is an essential part of the property. Each nuclide comes with its leading groups gave reviews and nuclear-mass business, this data is of own mass value different from all oth- updates of important aspects of the experimental origin, and thus has to be ers (presently about 3,200 known or field. The two sessions, each of four measured. H.-Jürgen Kluge of GSI at estimated) [1]. Thus the atomic talks, have been moderated by E. W. Darmstadt and the University of Heidel- masses are basic quantities of highest Otten and G. Werth from the Univer- berg explained how to perform “High- interest. High-accuracy mass mea- sity of Mainz. Several short talks of Precision Mass Measurements on Radio- surements allow to determine nuclear young researchers have been added. In nuclides in Storage Rings and Ion Traps.” and atomic binding energies and thus the following, we summarize the He noted that in the last decade new ideas have a huge field of application that invited talks, which gave an excellent have been introduced for high-precision extends beyond nuclear physics [2]. In overview of this very active field. mass measurements of short-lived radio- the case of short-lived exotic atomic Georges Audi of the CSNSM at nuclides that use the principle of ion trap- nuclei it ranges from the verification Orsay started the symposium with “The ping and cooling [4]. The new methods of nuclear models to a contribution History of Mass Spectrometry and the were pioneered on the small scale of ion towards the test of the Standard Atomic-Mass Evaluation.” He drew the traps by the triple-trap mass spectrometer Model, in particular with regard to the main lines from the early days of mass ISOLTRAP [5,6] at ISOLDE/CERN, weak interaction and the unitarity of spectrometry when Aston and Thom- and on the large scale of storage rings by the Cabibbo-Kobayashi-Maskawa quark son discovered isotopism, to the devel- the Schottky and isochronous mass spec- mixing matrix. As for mass measure- opment of Mattauch-Herzog mass trometry at the experimental storage ring ments on stable atoms, they now reach spectrometers in 1930s, and to the first ESR at GSI/Darmstadt [7,8]. In the mean a relative mass uncertainty of about installation of a high-precision Penning- time, a large fraction of all directly mea- 10−11. This extreme accuracy allows, trap mass spectrometer in 1986. After sured masses in the chart of nuclei have among others, to contribute to metrol- this historical account he developed been determined by these devices, and ogy, that is, the determination of fun- general ideas about data evaluation in across the world many other Penning- damental constants and a new definition nuclear physics and described the most trap facilities at accelerators are opera- of the kilogram, and to tests of quan- prominent features of the Atomic-Mass tional, in the building-up stage, or tum electrodynamics and Einstein’s Evaluation (AME), the reasons for its planned. The talk motivated and intro- energy-mass relation [3]. complexity, and how problems are faced duced the large variety of atomic and Several of these topics have been and solved. He explained why it was nuclear physics experiments with stored highlighted recently at a symposium found essential to create the NUBASE particles in ion traps [4]. on “Atomic High-Precision Mass Spec- evaluation and how he finally succeeded In the following presentation trometry” (http://www.dpg-tagungen. in having AME and NUBASE co- Georg Bollen from the National Super- de/prog/syam/index.html) in the frame- ordinated and published for the first conducting Cyclotron Laboratory at work of the annual meeting of the time together in December 2003 [1]. Michigan State University/East Lansing,

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took that ball and reported about “Preci- to the accuracy with which nuclear recently due to the employment of Pen- sion Mass Spectrometry of Rare Isotopes masses can be calculated in a mean-field ning traps coupled to fast injection of in America.” He again emphasized that approach and that chaotic motion inside ions. Selected results were taken from accurate masses of nuclides far away the atomic nucleus is responsible for this the ISOLTRAP facility at CERN and from the valley of beta-stability are most lack of predictability [13,14]. In view of the JYFLTRAP-IGISOL facility [21] at important for the understanding of the the important implications of this claim, the University of Jyväskylä. nuclear many-body system as input for for example, for nuclear astrophysics, its After this talk the subject changed the modelling of the synthesis of the ele- meaning was clarified with an empirical from mass spectrometry on radionuclides ments in the universe, and for tests of study of more than 2,000 nuclear masses. to high-precision mass measurements on fundamental symmetries. Because Pen- By use of Garvey-Kelson relations corre- stable ions. Reinhold Schuch of the ning-trap mass spectrometry offers lations among neighboring masses have Stockholm University reported on mass unprecedented accuracy and a very high been established where the root-mean- measurements with the SMILETRAP sensitivity, in America, too, several Pen- square deviation is below 100keV. This Penning-trap mass spectrometer, “A Pre- ning-trap mass spectrometers have been can be considered as a upper limit for the cision Mass Balance Using Highly or are presently being built. These current predictability of nuclear masses. Charged Ions.” It exploits the merits of projects make use of unique rare-isotope The afternoon session started off highly charged ions retrapped from an production facilities and thus contribute with “Recent Trends in the Determi- electron-beam ion source. These ions are to the worldwide effort to enhance the nation of Nuclear Masses” by Juha retarded in a first cylindrical Penning trap knowledge of nuclear binding energies Äystö of the University of Jyväskylä, before a fraction of them is sent to the [9]. The talk gave an overview of ongo- Finland. He reminded all participants hyperbolic precision Penning trap where ing activities and the perspectives of that the mass of a nucleus is a mirror their cyclotron frequency is measured reaching even more exotic nuclides: The of its binding energy [2]. It is the with a resolving power of 108 [22]. In Canadian Penning Trap mass spectrome- result of the strong interaction acting order to reduce the influence of mag- ter at Argonne recently started its experi- in the finite many-body system of pro- netic-field variations the cyclotron fre- mental program [10]. LEBIT at the tons and neutrons, and thus carries quencies of ions of interest and that of the Michigan State University [11] and fundamental information on the reference ions are measured within dura- TITAN at TRIUMF/Vancouver [12] are microscopic structure of the nucleus. tions as short as two minutes. Several in commissioning phase or under con- The measurement of binding energies mass measurements with a relative struction, respectively. with relative accuracies in the range uncertainty in the region of 0.3 to a few Although direct mass measure- from 10−6 to 10−8 is necessary to ppb have been performed by use of ions ments built the data basis, theoretical unravel the predicted new phenomena with charge states 1+ to 52+ [22]. The models are as important when it in nuclear structure of exotic nuclei nuclides investigated include 28,30Si for a comes to predict unknown nuclear with extreme proton to neutron num- new definition of the kilogram and the masses far away from the valley of ber ratios [15,16]. Precision measure- 76Ge-76Se pair [23] to extract the Q value stability that are not (yet) in experiments of nuclear masses also play an of double-beta decay for the search of mental reach. Piet Van Isacker from important role in nuclear astrophysics neutrinoless double-beta decay. GANIL at Caen discussed the “Theory and fundamental symmetries and Edmund Myers from Florida State and Predictability of Nuclear Masses.” interactions [17–19]. The talk pre- University reported about “Precision He reviewed the status of modern sented recent trends and in particular Mass Spectrometry with One and Two nuclear mass formulas [2]. This some precision mass measurements of Ions in a Penning Trap,” which had includes the elementary Weizsäcker exotic nuclei with high neutron been pioneered by David Pritchard at liquid-drop formula and its refine- excess, which are of interest for stud- MIT. In the 1990s Prichards group ments, such as the finite-range droplet ies of the nuclear structure and the developed a Penning-trap setup and model, as well as more microscopically shapes of nuclei, as well as measure- established an atomic mass table with founded attempts based on Hartree- ments of neutron-deficient nuclei of application to fundamental constants Fock theory and the shell model. Spe- interest with respect to nucleosynthe- in a class of its own, namely at an cial attention was paid to the recent sis in stellar processes [20]. These mea- uncertainty level of 10−10 [24]. The suggestion that there might be a limit surements have become possible only success of this mass spectrometer is

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based on several special features such restricted to precision measurements 19. A. Kellerbauer et al., Phys. Rev. Lett. as a dc-SQUID detector and the use of of atomic masses. One particularly 93 (2004) 072502. a “pulse and phase” technique, analogous exciting aspect is the combination of 20. D. Rodríguez et al., Phys. Rev. Lett. 93 to the Ramsey Separated-Oscillatory- positron and antiproton trapping. This (2004) 161104. 21. V. Kolhinen et al., Nucl. Instrum. Field method. In the last few years an recent development led to the creation Meth. A 528 (2004) 776. further technique has been developed: of neutral antimatter in the form of 22. I. Bergström et al., Nucl. Instrum. The two ions to be compared are posi- antihydrogen by the “recombination” Methods A 487 (2002) 618. tioned in the same trap in a coupled of simultaneously trapped antiprotons 23. G. Douysset et al., Phys. Rev. Lett. 86 magnetron orbit. Their cyclotron fre- and positrons [27–30]. (2001) 4259. quencies are thus measured simulta- More than 7,000 physicists 24. M. P. Bradley et al., Phys. Rev. Lett. 83 neously. This method suppresses the attended this year’s annual meeting of (1999) 4510. uncertainty due to, for example mag- the German Physical Society at Berlin. 25. G. Gabrielse et al., Phys. Rev. Lett. 82 netic-field fluctuations by two to three They brought more than 5,000 contri- (1999) 3198. 26. G. Gabrielse, Adv. At. Mol. Opt. Phys. orders of magnitude and allowed mass butions in the form of talks and post- 45 (2000) 1. comparison with uncertainties as low ers. The symposium on “Atomic 27. M. Amoretti et al., Nature 01096 −12 as 7 × 10 [3]. It led to the discovery High-Precision Mass Spectrometry” (2002) 1. of rotational state-dependent polariza- was certainly a highlight. 28. M. Amoretti et al., Nucl. Instrum. tion-induced cyclotron-frequency shifts Methods A 518 (2004) 679. 2 and a new test of Einstein’s E = mc . References 29. G. Gabrielse et al., Phys. Rev. Lett. 89 In 2003 the mass spectrometer was 1. G. Audi etal., Nucl. Phys. A 729 (2003) 3. (2002) 213401. relocated to Florida State University at 2. D. Lunney, J. M. Pearson, C. Thibault, 30. M. H. Holzscheiter, M. Charlton, M. M. Nieto, Phys. Rep. 402 (2004) 1. Tallahassee where additional mass Rev. Mod. Phys. 75 (2003) 1021. measurements at the 10−10 level using 3. S. Rainville, J. K. Thompson, D. E. Pritchard, Science 303 (2004) 334. single-ion techniques have been com- 4. H.-J. Kluge et al., Physica Scripta pleted. Further development of the T104 (2003) 167. −11 sub-10 two-ion technique is in 5. K. Blaum et al., Nucl. Instrum. Meth. B progress, in particular for a high-pre- 204 (2003) 478. cision atomic-mass comparison of tri- 6. F. Herfurth etal., J. Phys. B 36 (2003) 931. tium/helium-3, which will be relevant 7. T. Radon et al., Nucl. Phys. A 677 to neutrino-mass research. (2000) 75. Finally, the series of symposium 8. H.-J. Kluge, K. Blaum, C. Scheidenberger, Nucl. Instrum. Methods A 532 (2004) 48. talks was completed by Gerald Gabrielse 9. G. Bollen, Lect. Notes Phys. 651 of the University of Harvard who ext- (2004) 169. KLAUS BLAUM ended the range of applications to 10. J. Clark et al., Phys. Rev. Lett. 92 Johannes Gutenberg-Universität “Highly Accurate Measurements of Par- (2004) 192501. Mainz Germany ticle and Antiparticle Masses.” He pre- 11. S. Schwarz et al., Nucl. Instrum. Meth. sented a number of fundamental tests B 204 (2003) 507. via mass and charge-to-mass ratio com- 12. J. Dilling et al., Nucl. Instrum. Meth. B 204 (2003) 492. parisons including one of the most strin- 13. O. Bohigas and P. Leboeuf, Phys. Rev. gent test of the most fundamental Lett. 88 (2002) 092502. symmetry of physics, namely CPT 14. S. Åberg, Nature 417 (2002) 499. [25,26]. The mass comparison has been 15. J. Van Roosbroeck et al., Phys. Rev. performed for both positrons versus Lett. 92 (2004) 112501. electrons, that is leptons, and for anti- 16. S. Rinta-Antila et al., Phys. Rev. C 70 protons versus protons, that is, hadronic (2004) 011301(R). 17. K. Blaum et al., Phys. Rev. Lett. 91 matter. Furthermore, the audience was LUTZ SCHWEIKHARD (2003) 260801. reminded that ion trapping and in par- 18. M. Mukherjee et al., Phys. Rev. Lett. Ernst-Moritz-Arndt-Universität ticular the Penning trap is not 93 (2004) 150801. Greifswald Germany

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Report on the 15th Panhellenic Symposium on Nuclear Physics

This year the annual symposium of guished foreign colleagues. More than This year, the guest of honor was the Hellenic Nuclear Physics Society 75 participants from 5 countries Professor Dr. Peter Ring from the Phys- was held on May 27 and 28 at the attended the meeting. The large partic- ics Department of the Technical Univer- Physics Department of the Aristotle ipation of young colleagues at the sity of Munich. The Hellenic Nuclear University of Thessaloniki. M.Sc. and Ph.D. levels should be par- Physics Society honored Professor Ring In the Symposium the most recent ticularly noticed. for his pioneering work in the nuclear work of Greek nuclear physicists, There were 40 talks covering many body problem and named him a working within or out of Greece, was many areas from Nuclear Structure honorary member of the Society. reported. There were also invited and Reactions to Nuclear Astrophys- speakers from abroad, as it is a tradi- ics and Heavy Ion Physics and related GEORGIOS A. LALAZISSIS tion of the Society to invite distin- areas. Chair of the Organizing Committee

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IBA-Europhysics Prize 2005 for “Applied Nuclear Science and Nuclear Methods in Medicine”

The Executive Committee of the have been developed in the past for EPS has approved the recommendation fundamental experiments in nuclear of the Nuclear Physics Board according and neutron physics. The basis for an to the proposal of the IBA-EPS prize important application in medicine was selection Committee to award the IBA- prepared, the use of polarized 3He as Europhysics Prize 2005 to Prof. Dr. a contrasts agent to image the air- Werner Heil, Johannes Gutenberg Uni- spaces of the lungs and to check lung versität Mainz, Germany and Dr. Pierre functions. Jean Nacher, Laboratoire Kastler Bros- The IBA-Europhysics prize is sel, ENS Paris, France. The Prize is sponsored by the IBA (Ion Beam PROF. DR. WERNER HEIL attributed with the citation: “For the Applications) Executive Committee, development of spin polarized 3He tar- Chemin du Cyclotron, 1348 Louvain gets by optical pumping and their appli- la Neuve, Belgium. It will be deliv- cations in nuclear science and ered during the XIX Nuclear Physics medicine: nuclear physics, neutron low Divisional Conference “New Trends temperature physics and medicine.” in Nuclear Physics Applications and The two winners are pioneers in Technology” in Pavia, Italy from the art of polarizing 3He by the September 5–9, 2005. method of metastability exchange optical pumping (MEOP) and apply- PROF. CH. LECLERCQ-WILLAIN ing it to several fields (electron scat- President IBA-EPS Selection Committee tering on polarized 3He targets, Université libre de Bruxelles, polarization of neutron beams, con- B 1050 Bruxelles DR. PIERRE JEAN NACHER trast agent for NMR tomography). Powerful techniques of polarizing 3He

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2005 May 27–31 September 12–16 March 11–12 Aschaffenburg, Bavaria, Caen, France. 11th International MPI Heidelberg, Germany. “New Germany. SHIM 2005: Swift Heavy Conference on Ion Sources ICIS05. Trends in Nuclear, Atomic and Ions in Matter. Web: http://www.ganil.fr/icis05 Molecular Physics.” Web: http://www.gsi.de/SHIM2005 Web: http://www.mpi-hd.mpg.de/ September 12–17 heavy-ion/65/ June 14–18 Kos, Greece. Frontiers in Nuclear Lund, Sweden. International Con- Structure, Astrophysics, and Reac- March 13–20 ference on Finite Fermionic Systems, tions Conference (FINUSTAR). Bormio, Italy. XLIII International Nilsson Model 50 years. Web: http://www.inp.demokritos.gr/ Winter Meetings on Nuclear Physics. Web: http://www.matfys.lth.se/ ~finustar Web: [email protected] Nilsson October 3–7 March 19–23 June 20–25 Igazu, Argentina. The Sixth Latin San Servolo, Italy. FUSION06, Debrecen, Hungary. Exotic American Symposium on Nuclear International Conference on Reaction Nuclear Systems ENS’05. Physics and Applications. Mechanisms and Nuclear Structure Web: http://atomki.hu/~ens05/ Web: http://www.tandar.cnea.gov.ar/ at the Columb Barrier. misc/SLAFNAP6.php Web: http://www.lnl.infn.it/~fusion06/ June 28–July 1 Peterhof, St. Petersburg, Russia. October 16–22 March 29–April 1 LV International Meeting on Nuclear Dresden, Germany. Workshop on Kloster Banz, Bavaria, Germany. Spectroscopy and Nuclear Structure Critical Stability. Neutron-Rich Radioactive Ion “Frontiers in the Physics of Nucleus.” Web: http://www.mpipks-dresden. Beams—Physics with MAFF. Web: http://nuclpc1.phys.spbu.ru/ mpg.de Web: http://www.ha.physik.uni- nuclconf muenchen.de/maff/ October 17–21 workshop/ August 30–September 6 Beijing, China. Asia-Pacific Sym- Piaski, Poland. XXIX Mazurian posium on Radiochamistry 2005 May 16–20 Lakes Conference on Physics: APSORC-05. Debrecen, Hungary. Nuclear Phys- “Nuclear Physics and the Fundamen- Web: http://www.ihep.ac.cn/ ics in Astrophysics—II. tal Process.” apsorc2005 Web: http://atomki.hu/~npa2/ Web: http://zfjavs.fuw.edu.pl/ mazurian/mazurian.html December 15–20 May 16–22 Honululu, Hawaii, USA. “SCI- Bonn, Germany. International September 5–9 ENCE WITH RARE ISOTOPE Conference on Low Energy Antipro- Pavia, Italy. EPS XIX Nuclear BEAM.” Part of PACIFICHEM ton Physics (LEAP-05). Physics Divisional Conference 2005. Web: http://www.fz-juelich.de/ (NPDC19). Web: http://www.phy.cuhk.edu.hk/ leap-05 Web: http://www.pv.infn.it/~npdc19 gee/pachem05/ pacifichem.html May 23–26 September 10–14 Bonn, Germany. 6th International Zaragoza, Spain. Ninth Interna- 2006 Conference on Nuclear Physics at tional Conference on Topics in Astro- September 2–6 Storage Rings STOR105. particle and Underground Physics Rio de Janeiro, Brazil. Interna- Web: http://www.fz-juelich.de/ikp/ (TAUP). tional Conference on Nucleus- stori05/ Web: http://www.unizar.es/taup2005 Nucleus Collisions NN2006. Web: [email protected]

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Second Announcement

Call for Abstracts Asia-Pacific Symposium on Radiochemistry 2005 (APSORC- 05)

About the Conference per person per diem for double occupancy in a standard room. The third international conference in the series of Asia- A list of cheaper hotels will be provided upon request. Pacific Symposium on Radiochemistry (APSORC-05) will be held in Beijing, China, during 2005 October 17–21. The Language first APSORC was held in Kumamoto, Japan (1997), and The conference language is English. the second in Fukuoka, Japan (2001). The conference provides an international forum for presentation and discussion of current and emerging sciences in all fields of radiochem- Organization istry and nuclear chemistry, and their applications to vari- Under the supervision of the APSORC International Com- ous fields. It aims to promote academic activities in mittee (APSORC-IC), the Symposium is co-organized by: nuclear, radiochemical and related sciences. Scientists, Chinese Nuclear & Radiochemistry Society (CNRS) engineers and students from universities, institutes, labora- China Institute of Atomic Energy (CIAE) tories and industries throughout the world are encouraged Institute of High Energy Physics (IHEP) to participate and make contributions. Peking University (PKU) Tsinghua University (THU) Venue and hotel The Symposium will be held at the Grand View Garden APSORC-05 is sponsored by the: Hotel in Beijing. It is a four- star hotel with a beautiful Chinese Academy of Sciences (CAS) view. The hotel website (http://www.gvghotel.com) is in National Natural Science Foundation of China both English and Chinese languages. A discount price will (NNSFC) be provided to pre-registered participants at the rate of US$ Chinese Chemical Society (CCS) 60 per person per diem for single occupancy and US$ 40 Chinese Nuclear Society (CNS)

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Query sheet AU Q1: cut off?. GNPN_A_125510.fm Page 1 Thursday, August 11, 2005 12:45 PM

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2005 September 26–December 2 October 19–21 September 10–14 Seattle, Washington, USA Caen, France Workshop on Zaragoza, Spain Ninth Interna- Nuclear Structure Near the Limits Reactions with SPIRAL 2 tional Conference on Topics in Astro- of Stability http://www.ganil.fr/research/ particle and Underground (TAUP) http://www.int.washington.edu/ developments/spiral2/ http://www.unizar.es/taup2005 PROGRAMS/05–3.html October 31–November 1 September 10–15 September 28–30 CERN, Geneva, Switzerland Sant Feliu de Guixols (Costa Santiago de Compostela, Spain ISOLDE PAC Meeting Brava), Spain EuroConference R3B-EXL Workshop http://isolde.web.cern.ch/ISOLDE/ on Ultracold Gases and their http://www.usc.es/genp/Meetings/ Applications. R3BEXL Sant 05/ November 3–10 Web: http://www.esf.org/esf Bordeaux, France 10th Geant4 genericpage.php?section October 3–7 Conference = 10&language = 0&gene Iguazu, Argentina The Sixth http://geant4.in2p3.fr/2005/ ricpage = 2 Latin American Symposium on Nuclear Physics and Applications November 18–19 September 12–16 http://www.tandar.cnea.gov.ar/ Groningen, The Netherlands Caen, France 11th International misc/SLAFNAP6.php NuPECC Meeting Conference on Ion Sources ICIS05 http://www.nupecc.org/misc/ http://www.ganil.fr/icis05 October 3–7 communications.html Zurich, Switzerland Tracking in September 12–17 High Multiplicity Environments November 23–25 Kos, Greece Frontiers in Nuclear (TIME ‘05) Brussels, Belgium 3rd Interna- Structure, Astrophysics, and Reac- http://ckm.physik.unizh.ch/time05/ tional Conference on Education and tions Conference (FIN Training in Radiological Prot http://www.inp.demokritos.gr/ October 10–12 http://www.etrap.net/ ~finustar CERN, Geneva, Switzerland Nuclear Physics & Astrophysics at November 28–29 September 19–24 CERN - NuPAC Caen, France EURISOL Town Milos Island, Greece 6th Research http://cern.ch/nupac Meeting Conference on Electromagnetic Inter- http://www.ganil.fr/eurisol/ actions with Nucleons an 2005) October 12–14 http://www.iasa.gr/EINN 2005/ Frascati, Italy Workshop on November 28–December 1 “Nucleon Form Factors” Catania, Italy IWM2005-Inter- September 21–25 http://www.Inf.infn.it/conference/ national Workshop of Multifrag- Kazimierz Dolny, Poland XII nucleon05/ mentation and related topic Nuclear Physics Workshop Marie http://www.dg-talengine.it/ and Pierre Curie “Nuclear Struc- October 16–22 iwm2005/index.htm ture and Reactions” Dresden, Germany Workshop on http://kft.umcs.lublin.pl/wfj/ Critical Stability December 12–14 http://www.mpipks-dresden.mpg. de GSI Darmstadt, Germany September 25–October 2 PANDA Collaboration Meeting Albena, Bulgaria Third Sandan- October 17–21 http://www.ep1.rub.de/~panda/ ski Coordination Meeting on Beijing, China Asia-Pacific Sym- auto/home.htm Nuclear Science. posium on Radiochamistry 2005 Web: http://beo-db.inrne.bas.bg/ APSORC-05 albena 2005/ http://www.ihep.ac.cn/apsorc2005

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December 15–20 March 19–23 Web: http://indico.cern.ch/ Honululu, Hawaii, USA “SCI- San Servolo, Venezia, Italy conferenceDisplay.py?c ENCE WITH RARE ISOTOPE FUSION06, International Confer- onfld = 059 BEAMS”, Part of PACIFICHEM ence on Reaction Mechanisms and 2005 Nuclear S Coulomb Barrier July 3–7 http://www.phy.cuhk.edu.hk/gee/ http://www.Inl.infn.it/~fusion06/ Cortina d’Ampezzo, Italy 7th pachem05/pacifichem. html International Conference on Radio- June 12–14 active Nuclear Beams (RNB7). 2006 GSI Darmstadt, Germany Web: http://rnb7.pd.infn.it/ January 29–February 3 PANDA Collaboration Meeting Bormio, Italy XLIV Interna- http://www.ep1.rub.de/~panda/ August 21–26 tional Winter Meeting on Nuclear auto/ home.htm Santos, Sao Paulo, Brasil 18th Physics. International IUPAP Conference on Q1 Web: [email protected]. June 20–23 Few-Body Problems in Physics (FB St. Goar, Germany 2nd Interna- Web: http://www.fb18.com.br/ March 6–10 tional Conference on Collective Dresden, Germany PANDA Col- Motion in Nuclei under Extreme September 2–5 laboration and Physics Meeting (COMEX 2). Vienna, Austria PANDA Collab- http://www.ep1.rub.de/~panda/ Web: http://www.ikp.physik.tu- oration Meeting auto/ home.htm darmstadt.de/comex2/ http://www.ep1.rub.de/~panda/ auto/ home.htm March 17–18 June 25–30 Athens, Greece NuPECC Meeting CERN, Geneva, Switzerland September 2–6 http://www.nupecc.org/misc/ International Symposium on Rio de Janeiro, Brasil Interna- communications.html Nuclear Astrophysics Nuclei in the tional Conference on Nucleus- Cosmos — NI. Nucleus Collisions NN2006 [email protected]

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