Nuclear Physics Nuclear Physics News is published on behalf of the Nuclear Physics European Collaboration Commit- tee (NuPECC), an Expert Committee of the Euro- pean Science Foundation, with colleagues from News Europe, America, and Asia. Volume 15/No. 1
Editor: Gabriele-Elisabeth Körner 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) G. van der Steenhoven, Amsterdam 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, Louvain-la-Neuve; Brasil: M. Hussein, São Paulo; Bulgaria: D. Balabanski, Sofia; Canada: J.-M. Poutissou, TRIUMF; K. Sharma, Manitoba; C. Svensson, Guelph; China: W. Zhan, Lanzhou; Croatia: R. C˘aplar, Zagreb; Czech Republic: J. Kvasil, Prague; Slovak Republic: P. Povinec, Bratislava; Denmark: K. Riisager, Århus; Finland: M. Leino, Jyväskylä; France: G. De France, GANIL Caen; B. Blank, Bordeaux; M. Guidal, IPN Orsay; Germany: K. D. Gross, GSI Darmstadt; 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. 1, 2005, Nuclear Physics News 1 Nuclear Physics Volume 15/No. 1 News
Contents Editorial ...... 3 Letter to the Editor ...... 4 Laboratory Portrait High Energy Accelerator Research Organization in Japan (KEK) by Shoji Nagamiya ...... 5 Feature Articles Neutrino Physics by Lothar Oberauer and Caren Hagner ...... 12 Structural Evolution in Nuclei: The Rich Structures of a Simple Hamiltonian by J. Jolie and R. F. Casten ...... 20 Facilities and Methods Application of Low Energy Spin Polarized Radioactive Ion Beams in Condensed Matter Research by R. F. Kiefl, K. H. Chow, W. A. MacFarlane, G. D. Morris, C. D. P. Levy, and Z. Salman ...... 26 Meeting Reports Report on the 8th Nuclei in the Cosmos Conference by John M. D’Auria ...... 33 International Conference on Nuclear Data for Science and Technology by Robert C. Haight and Mark B. Chadwick ...... 34 News and Views...... 36 Calendar ...... 39
Cover illustration: A photo of High Energy Accelerator Research Organization in Japan (KEK) which is located on the foothill of the Tsukuba Mountain. The largest ring at KEK is an electron-positron collider called the B-Factory. A small ring inside the B-Factory is the 12 GeV Proton Synchrotron, where nuclear physics activities are conducted. A ring adjacent to and outside the B-Factory ring is a photon factory with 2.5 GeV electrons (see article on page 5).
2 Nuclear Physics News, Vol. 15, No. 1, 2005 editorial
Be Ready: The International Year of Physics is Taking Off!
It has been a long and hard way preparatory meetings were held in Graz European organizations under the since the European Physical Society (July ’03) and Montreal (March ’04), leadership of EPS. proposed in late 2000 to declare 2005 in which many events planned The main objective of WYP 2005 as the “World Year of Physics” (WYP). worldwide have been presented—see is to promote physics, to highlight its This initiative has steadily made the report on the Montreal meeting by importance and impact in everyday life, progress in its acceptance by the Christophe Rossel, in Europhysics and to remind us that physics is part of international organizations. The IUPAP News 35 (3), p. 96, 2004. More recently, human culture. Its main target is the endorsed it in October 2002, at its in October 2004, the European WYP general public, and particularly young General Assembly in Berlin. The coordinators met in Mulhouse to people. This will be exemplified in the General Conference of UNESCO voted present their activity plans, to share “kick-off” meeting of the International to accept it in Paris, in October 2003. their experience, and to try to co- Year of Physics, Physics for Tomorrow, Finally, in June 2004, in New York, the ordinate events between European which is being held at the UNESCO General Assembly of the United countries as much as possible. The level headquarters in Paris, from 13–15 Nations Organisation passed by of preparation of WYP activities was January 2005. This conference, open to acclamation a resolution declaring 2005 found to be quite advanced: museum the general public, aims at capturing the as the “International Year of Physics” exhibits for the general public around attention of the international press and (IYP) (see: http://www.un.org/Depts/ Einstein’s legacy and physical sciences media, so that events and celebrations dhl/resguide/r58.htm and www.un.org/ in general, radio and television organized around the world throughout News/Press/docs/2004/ga10243.doc. programs, commemorative coins and the year will attract public and media htm.). At that point, one should recall stamps, street events on physics themes, attention. Half of those attending the that only the UN General Assembly has theatre plays, conferences, and so on. meeting will be young students (500, the power to declare “International” In Portugal, a coordinator in charge of with age ~16–21) coming from all over years. So the “World Year of Physics” WYP relations and organization has the world, including developing is now the “International Year of been officially accredited by the countries from Africa and Asia. They Physics”! The UN resolution on IYP Portuguese government. Also, more will have the opportunity to closely has been sponsored by the permanent global activities, at the European level interact with prestigious speakers delegations of Brazil, France, Lesotho, and worldwide, are well on the way. (among them several Nobel laureates) Monaco, Portugal, Singapore, and the These include activities such as who will present their views on the role United Kingdom, and presented by the “physics enlightens the world” (a relay of physics in society and in solving Lesotho ambassador to the UN, Dr. of light signals around the globe), 21st-century challenges (energy, Lebohang K. Moleko (see: http:// “physics talent search,” and “physics environment, development…), on its www.un.org/webcast/ga.html). Dr. as a cultural heritage” (a full account trans-disciplinary character and its Moleko should be thanked for his of those global initiatives is given on influence on other disciplines, on novel efforts to get the resolution passed. the Web page http://www.wyp2005. approaches to physics teaching and In the meantime, physicists and org). Funding for WYP activities is also scientific education, and so on. Physical Societies did not wait for the growing quickly both at the local and As expected from an event that vote of the resolution at the UN European level: the European opens a year where increasing the assembly to start to plan and organize Commission has recently decided to public awareness of physics and events, actions, exhibits, and support WYP activities in Europe by physical sciences is a major goal, the conferences at the national and funding, at the 2M€ level, via the “kick-off” conference will exhibit international level. Two WYP “Science and Society” program, many marked features of general public
The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.
Vol. 15, No. 1, 2005, Nuclear Physics News 3 editorial
interest. This must be the rule for all proactive in sharing his visions and MARTIAL DUCLOY the events planned throughout the year convictions about physics and science EPS Past-President 2005, and one expects every physicist with Society at large. Chair of the WYP International to accept his responsibility in this Steering Committee respect during the coming year, being Happy and fruitful Year 2005!
Letter to the Editor
In the article “Studies of Elemental is clearly not correct. Unfortunately, the the article seemingly ignores the Synthesis in Exploding Stars Using original statement “Until recently the excellent research using radioactive DRAGON and TUDA with technology has not been available to beams that have been performed by Radioactive Beams at ISAC,” Nuclear obtain required information directly on various laboratories for about 15 years, Physics News, vol. 14 no. 2, we claim the rates of radiative capture reactions for example, see review by M. S. Smith that “Until recently the technology has involving such short-nuclei species, and K. E. Rehm, in Ann. Rev. of Nucl. not been available to obtain required with the exception of the first Part. Sci. 51 (2001)91. This was not our information on the rates of reactions measurement at the Louvain-la-Neuve intent and we apologize to all on this involving such short-nuclei species, facility some years ago,” somehow was matter. with the exception of the first inadvertently changed. As was correctly measurement at the Louvain-la-Neuve pointed out to me by Carmen Angulo JOHN M. D’AURIA facility some years ago.” This statement of Louvain-la-Neuve, the statement in AND LOTHAR BUCHMANN
4 Nuclear Physics News, Vol. 15, No. 1, 2005 laboratory portrait
High Energy Accelerator Research Organization in Japan (KEK)
1. Introduction experiment). Namely, it probes a deep interior of the In 1997 three institutions in Japan, In addition, KEK is currently nucleus and, perhaps, modifies the National Institute for High Energy promoting a new accelerator structure of the nucleus itself. Also, the Physics (the original KEK), Institute of construction, called the J-PARC, by nucleus might play as a micro- Nuclear Study (INS) at University of collaborating with Japan Atomic laboratory to investigate new nuclear Tokyo, and Meson Science Laboratory Energy Research Institute (JAERI). forces, that is, the interactions between at Department of Physics of University These activities are summarized in hyperon and nucleon, and even between of Tokyo, joined together to form a new Figure 1, are they described in this hyperon and hyperon. institution called the High Energy article. Hypernuclear physics programs at Accelerator Research Organization. KEK-PS have been carried out with The nickname of this new-born 2. The 12 GeV Proton Synchrotron three secondary beam lines of charged institution is called again the KEK. pions and kaons: K6, K5, and K2. The new KEK has two research 2.1. Hypernuclear Physics Although the beam intensities, the kaon institutes: Institute of Particle and The hypernucleus is a new type intensity in particular, are not the Nuclear Studies (INPS) and Institute of nucleus for which a hyperon, Λ, Σ, and highest in the world, many interesting Materials and Structure Science Ξ, or two hyperons are embedded in a and important experiments have been (IMSS). The main activity at INPS is normal nucleus as an impurity, by conducted by using a unique high-energy physics, whereas an active having a new quantum number of spectrometer together with detector nuclear physics research is also strangeness. Because the hyperon does systems. conducted at this INPS. not obey a nucleonic Pauli principle, it The Superconducting Kaon In nuclear physics research at KEK can be bound deeply inside the nucleus. Spectrometer (SKS) is a large three major areas are the highlights. The first area is the research on the properties of nuclear matter as viewed from quantum chromo dynamics (QCD). Experiments are in progress at the 12 GeV Proton Synchrotron (12 GeV PS). There, primary proton beams as well as kaon beams are used. In addition, KEK supports nuclear matter physics by funding a US–Japan collaboration program at BNL (PHENIX experiment). The second area is nuclear spectroscopy, primarily hypernuclear spectroscopy with kaon- and pion- beams at the 12 GeV PS, and nuclear spectroscopy far from the stability line by using a method of the target fragmentation. Finally, the third area is neutrino physics by creating neutrino beams at the 12 GeV PS and detecting them at Superkamiokande (K2K Figure 1. Summary of nuclear physics activities at KEK.
Vol. 15, No. 1, 2005, Nuclear Physics News 5 laboratory portrait
nucleus, was observed [1]. At K2 beam line, an experiment to study the hypernuclei with strangeness –2 has been carried out by applying an emulsion-scintillating fiber hybrid method. A new event that shows the 6 production of ΛΛ He was clearly observed, as shown in Figure 3 [2]. It unambiguously determines the mass of this double-Λ hypernucleus with Λ−Λ
interaction energy of ∆BΛΛ = 1.01 ± 0.20 + 0.18/–0.11 MeV. This value is smaller than the old value of about 4 MeV estimated from the old emulsion data in the 1960s. This event stimulated Figure 2. A gamma-ray energy spectrum observed in KEK-PS E419 for the a large number of theorists and, as a 7 + +γ Li(F ,K ) reaction. result, the importance of ΞN-ΛΛ mixing effect has been pointed out. acceptance (100 msr) magnetic gamma-ray transition between the 2.2. K-Mesons in Nuclei spectrometer with a good energy ground state spin-spin doublet was Recently, a tribaryon state, + resolution (2 MeVFWHM), installed at the measured for the first time, as shown S (3140), was discovered in the neutron K6 beam line. It has been used to in Figure 2. Also, from the energy spectrum from K- absorption produce efficiently Λ hypernuclei with measurement of E2 transition rate of an reaction on 4He target [3]. Furthermore, the (Z+,K+) reactions. In the recent excited state with Doppler-Shift another strange tribaryon state, experiments on non-mesonic weak Attenuation method a nuclear shrinkage S0(3115), was measured in the proton 5 12 decay study of Λ He and Λ C, successful of ~19%, supposedly due to the spectrum [4]. The observed proton and measurements were preformed to detect existence of a Λ hyperon inside the neutron spectra are shown in Figure 4. both n-p and n-n pairs from Λp→np and The aforementioned experimental Λn→nn processes, respectively. It search was triggered originally by a enabled us to determine branching theoretical work by Akaishi and ratios of these two decay modes Yamazaki [5], which predicts the unambiguously. Recently, double existence of a deeply bound kaonic state charge-exchange (Z-, K+) reactions were (I = 0, Z = 1 and ~100 MeV in binding utilized to produce Σs and neutron-rich energy). However, the data cannot be Λ hypernuclei for the first time. understood well by this theory alone. A new detector system, called the For example, the observed peak in Hyperball Detector, was constructed for the neutron spectrum corresponds to the hypernuclear gamma-ray measure- theoretical prediction, whereas an even ments. It consists of 14 germanium lower-energy state, S0(3115) with I =1, 2 detectors, and it succeeded to measure Z = 0 and MS0 ~ 3117 MeV/c , is now gamma-ray transitions of Λ hypernuclei found in the proton spectrum. This mass with a few keV energy resolution. With is even smaller than the mass of the I = this detector a new era of high precision 0 state. In addition, the binding energy spectroscopy was open in the of kaon in both S0(3115) and S+(3140) hypernuclear study. The first successful Figure 3. A photograph of the emulsion is as large as twice of the theoretically 6 measurement was performed together tracks, showing the production of ΛΛ He predicted value. 7 with the SKS spectrometer for Λ Li; the and its sequential weak decays. Thus, the nature of the observed
6 Nuclear Physics News, Vol. 15, No. 1, 2005 laboratory portrait
restoration of chiral symmetry breaking excess of any calculations, and this for a kaon in nuclear matter. excess cannot be interpreted by our To pursue experimental research common knowledge. Perhaps, the tail toward this direction, high-intensity could be due that the mass of a ω and/ kaon beams that can be provided by the or ρ mesons, which decay inside the J-PARC (see later) would be needed. nucleus, are distorted to a smaller value than the free ω meson mass. 2.3. Vector Mesons in Nuclei Although further studies are In the North Hall of the 12 GeV-PS, required, the observed excess in the there is a primary beam line called the yield in the tail region is interesting EP1B. There, an experiment has been performed to measure lepton pairs from 2.4. K2K Neutrino Experiment vector mesons in nuclei. The purpose In 1998, a clear evidence for of these measurements is to study how neutrino oscillations was first reported the meson gets buoyancy in the nucleus. in the study of atmospheric neutrinos It is known that the mass of a bare at the Super-Kamiokande [6]. Neutrino quark is light, whereas, once it is bound oscillation occurs among the three (confined) to form a meson or a known flavors of neutrinos when nucleon, it gains an additional mass. neutrinos carry non-zero mass and The aim of the present experiment was mixing. to measure how the mass of a meson is The aim of the K2K experiment is distorted if the meson is imbedded to confirm the neutrino oscillation inside the nucleus and, hopefully, to phenomenon, using muon-neutrino Figure 4. Missing mass spectra study the chiral properties of quarks in beams produced by the 12 GeV PS. The obtained by K- on 4He for proton nuclear matter. near detectors at KEK measure the (upper) and neutron (lower). The “p A spectrometer was constructed to neutrino flux and energy spectrum trigger” requires an emission of a measure electron-positron pairs from immediately after neutrino production, ρ ω φ charged pion originated not from the the decays of , , and mesons. In and thus, neutrino events before reaction vertex but from opposite side Figure 5, invariant mass spectra for neutrino oscillation effects can be to the observed nucleon (solid circle). these pairs after subtracting background detected. The beam was directed The triggered events show a clear are shown. A clear peak corresponds to toward the Super-Kamiokande detector ω excess compared to slightly off-window the mass of the meson. located 250 km away from KEK. The events (open circle). An interesting observation is that a energy spectrum of the neutrino beam tail is observed to the left of the peak in is similar to that of atmospheric
states is still unclear. Nevertheless, the observed large value of kaon binding energy is interesting. Furthermore, as indicated by the theory of Akaishi and Yamazaki [5], this kaon might play a role as a catalyzer to induce the formation of an extremely high-density system. If this is the case, a further study of properties of kaon in nuclear matter for a variety of nuclei is intriguing, in particular, in terms of the study of a Figure 5. Observed invariant mass spectra of e+e- pairs from nuclear target.
Vol. 15, No. 1, 2005, Nuclear Physics News 7 laboratory portrait
with those expected from the targeted at a wide range of fields, using atmospheric neutrino oscillation results K-meson beams, neutrino beams, published previously by Super- neutron beams, and muon beams, to Kamiokande, which can only be cover nuclear and particle physics, attributed to the effects of neutrino materials science, biology, and nuclear oscillations. engineering, where these beams will be created by bombarding high-power 3. J-PARC Project proton beams on nuclei at rest. The accelerator is called the J-PARC, which 3.1. Overview and Progress is an abbreviation of Japan Proton Several years ago, KEK and the Accelerator Research Complex. Japan Atomic Energy Research Construction of the J-PARC facility Institute (JAERI) started work on a joint started in 2001 and the provision of Figure 6. Distortion of neutrino energy venture to construct a new proton beams is set to commence in the spring spectrum observed at Super- accelerator at the highest beam power of 2008. Construction work is currently Kamiokande (data points). Labeled by in the world. The new accelerator is in full swing in both areas of accelerator “Without oscillation” represents expectation in the absence of neutrino oscillations. Also shown is the expected spectrum taking into account neutrino oscillation effects .
neutrinos. Data-taking began in 1998. Data analysis and understanding of detector systematics have been continuously improved. After the analysis of the five- year data taken until May 2004, the following results are obtained: (1) 107 events have been observed at Super- Kamiokande, whereas the expected number is 151 (+12, –10) for no- oscillation hypothesis. (2) The observed neutrino spectrum reveals exactly the type of distortion expected from neutrino oscillation effects, as shown in Figure 6. Based on these results, two points are concluded: (1) If there is no oscillation, the probability to detect only 107 events and to obtain the observed distortion in the energy spectrum is negligible (at the level of 10-4). Namely, the neutrino carries a finite mass at the confidence level of Figure 7. Artist’s impression of the completed J-PARC facilities (upper) and the 99.99%. (2) K2K results are consistent current status of construction (lower).
8 Nuclear Physics News, Vol. 15, No. 1, 2005 laboratory portrait
construction and civil engineering. The have interests in J-PARC, please visit 1.1 GeV/c. Emphasis of the first photo, shown in Figure 7, illustrates the http://j-parc.jp/index.html. proposal is to measure nuclear states present status of construction. with strangeness of S = –1 and –2. The The accelerator complex, which 3.2. Day-1 Experiments at J-PARC second Day-1 proposal sets a high consists of a linac, followed by a Proposed nuclear physics priority on the measurements of a kaon synchrotron to accelerate proton beams experiments at J-PARC are classified implanted inside the nucleus. These two up to 3 GeV. These beams will be sent into two categories: strangeness nuclear experiments are the natural extension to a laboratory for materials and life physics and hadron physics. The of the present experiments conducted science with neutron and muon beams. classification is based on the difference at the 12 GeV PS at KEK, as described Some of the proton beams from the 3 in the beam requirements: The former in Sec. 2.1. and 2.2. GeV synchrotron ring will then be sent will use secondary kaon beams in Finally, about 16 experiments for to another 50 GeV synchrotron ring. medium energies of 1~2 GeV/c, Phase-1 were proposed at the Hadron After being accelerated there, one beam whereas the latter will use either higher Experimental Facility. Most of the will be sent to the hadron experimental energy secondary beams or the 50-GeV proposals ask for kaon beams, whereas facility to produce primarily kaon primary proton beam. Most of the other beams such as high momentum beams, with another beam being guided proposed experiments focus the quark primary beams are also requested. toward a neutrino beam line. Neutrinos many-body world from the viewpoint Because the first beam at the J- are then measured using the Super of QCD. PARC will be available in 2008, an Kamiokande detector 300 km away. In 2002, about 30 proposals were official call for the proposals will be Because the performance of the sent to the J-PARC Project Office. A made soon, most likely within 2005. accelerator is largely determined at the preliminary PAC was formed to discuss first stage of the linear accelerator, the these proposals. Proposals are classified 3.3. T2K Neutrino Experiment development of technology for this into four categories. The first one is a T2K (Tokai-to-Kamioka) experi- portion is of crucial importance. At large-scale neutrino experiment, which ment is a next generation long baseline the beginning of November 2003, a will be described in the next subsection. neutrino oscillation experiment, using full prescribed performance was The second is “Day-1 experiments” that neutrino beams from J-PARC. The successfully attained. can be started immediately after the muon neutrino beam produced by the J-PARC will be open to the whole turn-on of the beams at the Hadron 50-GeV PS in J-PARC is directed to and world as an international facility. The Experimental Facility. The third is detected by the Super-Kamiokande at number of applicants from North “Phase-1 experiments” that can be 295 km from J-PARC. The intensity of America and Europe in relation to planned in the Hadron Experimental the neutrino beam will be about 100 nuclear and particle physics has already Facility while not ready on Day-1. The times of the past K2K experiment at the exceeded the number of Japanese fourth category requires a new beam 12 GeV PS. researchers. This project is expected to line and a new experimental hall. The main goals of the experiment boost levels of participation from the Concerning experiments related to are: (1) A discovery of an undetected Asia and Oceanic regions in neutron ν →ν the fourth category, the J-PARC Project oscillation mode µ e appearance, related fields. Work on the necessary ν Office decided to prepare a third and (2) a precise measurement of µ preparations to accommodate such extraction line from the 50 GeV PS, disappearance. Sensitivity of the needs is also going ahead in cooperation 2 θ although no further considerations have unknown mixing sin 2 13 is 0.006 (90% with local governments including been given at the present stage. The CL), which improves the present upper Tokai-mura Village and the Ibaraki neutrino program (the first category) limit by about a factor of 20. As a Prefecture. was not on the budget table when the possible future extension, a search for In about 2010 it is anticipated that proposal was sent. Later, the budget for CP violation in the neutrino sector is J-PARC will develop into one of the this project was approved by the envisaged by multiplying the beam leading centers in the world. With that Government. power and constructing a ~1 Mton dream in mind, the project team is The Committee selected two water Cherenkov detector “Hyper- working day and night to forge ahead proposals for Day-1 at high priority. Kamiokande.” with construction work. For those who Both of them use kaon beams at 1.8 and The T2K experiment has been
Vol. 15, No. 1, 2005, Nuclear Physics News 9 laboratory portrait
developments. For further information of the TRIAC, refer to [8].
4.2. PHENIX Experiment at RHIC Quarks are confined inside hadrons and cannot be taken out as free particles. Lattice-QCD simulations, however, predicted the existence of a new phase of hadronic matter at high temperatures, called the quark-gluon plasma (QGP). In this phase, quarks Figure 8. Overview of the T2K experiment. and gluons are liberated from confinement and move freely. It is believed that the QGP existed in the Early Universe until ~10 µsec approved by the Government in 2003 electron cyclotron resonance ion-source immediately after the Big Bang. Recent and the construction started in April (CB-ECR), and a linac complex, which theoretical calculations have also 2004. The data taking will start in the comprises a split-coaxial RFQ predicted the existence of a liberated early 2009. International collaboration (SCRFQ-) linac, an interdigital-H type quark soup at a high baryon density has been formed. About 180 collabora- (IH-) linac, and a superconducting region, which may have relevance to tors from 61 institutions in 12 countries (SC-) linac. the inner core of the neutron star. (except students) signed up on the letter Primary protons as well as heavy- It is believed that a high-energy of intent as of August, 2004 [7]. ions are supplied from 20 MV Tandem heavy-ion collision is a unique tool to R&D work including a design of the accelerator, to produce radioactive beam line components has been in nuclei via nuclear fusions, transfers, and progress at KEK, with close fissions. For example, an expected cooperation with participating fission rate with 3 µA protons and UC- institutions in the T2K. Final design of target is 1.5 × 1011 fissions/sec. With the entire neutrino beam facility will the aid of the CB-ECR, which is a finish by March 2005. The construction charge state breeder for the mass of the upstream portion of the decay separated singly charged ions, an volume has been already started in efficient acceleration of the neutron- 2004. The design of neutrino detectors rich medium- or the medium-heavy in J-PARC site is also in progress. nuclide is available for studies in various research fields, such as in 4. Other Nuclear Physics Activities nuclear physics, nuclear astrophysics, nuclear chemistry, and materials 4.1. TRIAC science. Low-energy RNBs up to 1.1 The TRIAC (Tokai Radioactive Ion MeV/u are ready to use from the end Accelerator Complex) facility is a of 2004 and more energetic RNBs from Figure 9. Momentum spectra of neutral radioactive nuclear beam (RNB) 5 to 8 MeV/u will be also planned in pions in p-p collisions (stars), and as facility based on an isotope separator the near future by connecting the IH- compared with those in Au-Au central on-line (ISOL) and a post acceleration linac to the SC-linac. collisions (closed circles) at c.m.s. system [8]. It has been constructed at This facility will be open for users energy of 200 GeV per nucleon pair. the Tandem facility in Tokai-site of from mid FY2005. Radioactive isotopes Yield in p-p collisions are scaled with JAERI under the collaboration of KEK (102 types) in 18 elements have so far the number of binary collisions and JAERI. The facility consists of the been extracted as mass separated RNBs obtained from the Glauber model ISOL, an 18 GHz charge-breeding from ISOL system in the beam calculation.
10 Nuclear Physics News, Vol. 15, No. 1, 2005 laboratory portrait
create high quark density matter, to and the hindrance is caused by an method of Antisymmetrized Molecular study properties of an exotic quark energy loss of a parton (ancestor of a Dynamics. matter in a laboratory. A new era toward pion) via strong interaction while this direction began when the passing through the matter. Acknowledgments Relativistic Heavy Ion Collider (RHIC) This article was created from [9] at Brookhaven National Laboratory 4.3. Nuclear Theory Group contributions from individuals who are started its operation in 2000. RHIC can The research that is currently in either KEK members or members provide Au-Au head-on collisions at progress by the nuclear theory group at closely related to KEK. They are: T. 200 GeV per nucleon pair. KEK ranges from hadron physics to Nagae (Sec. 2-1 & 3-2), M Iwasaki The Japanese group has been exotic nuclei including unstable nuclei, (Sec. 2-2), H. En’yo (Sec. 2-3), K. participating in the PHENIX hypernuclei and kaonic nuclei. Nishikawa (Sec. 2-4), T. Kobayashi experiment [10], under the US–Japan Recently, new forms of hadron and (Sec. 3-3), H. Miyatake (Sec. 4-1), H. cooperation program in the field of high hadronic matter have been the focus Hamagaki (Sec. 4-2), and O. energy physics, funded by KEK. The from both theoretical and experimental Morimatsu (Sec. 4-3). Thanks go to all group consists of members from KEK, sides. In the theory group a pentaquark these individuals. U. of Tsukuba, U. of Tokyo, Waseda baryon is studied in the QCD sum rule U., Hiroshima U., and Nagasaki and in the flux-tube model. New states References Institute of Applied Science. The of the pentaquark baryon are also 1. K. Tanida et al., Phys. Rev. Lett. 86 Japanese group constructed several key predicted. A new phase of quark matter, (2001) 1982. detector subsystems in PHENIX, and color ferromagnetic phase, is proposed 2. H. Takahashi et al., Phys. Rev. Lett. 87 the group has been playing a leading as well. In addition, a theoretical (2001) 212502. role in executing experimental runs and investigation of how the restoration of 3. T. Suzuki et al., Phys. Lett. B 597 (2004) analyzing data. 263. chiral symmetry in hot matter affects 4. M. Iwasaki et al., nucl-ph:0310018 Many interesting results have been on the observed spectrum of hadrons submitted to PLB. obtained [11]. One example is shown has been conducted. 5. Y. Akaishi and T. Yamazaki, Phys. Rev. in Figure 9. It shows momentum spectra Another highlight is that the C 65 (2002) 044005. of neutral pions in both p-p collisions existence of deeply bound kaonic nuclei 6. Y. Fukuda et al., Phys. Rev. Lett. 81 and central Au-Au collisions, where the has been theoretically predicted, by (1998) 1562. yield in p-p collisions is scaled with the showing that the density is much higher 7. http://neutrino.kek.jp/jhfnu 8. H. Miyatake and H. Ikezoe for the number of binary collisions N . The than the normal nuclear matter density coll TRIAC collaboration, Nucl. Phys. N scaling should hold in the zeroth coll once the kaon is bound inside the News, 14 (4), 37(2004). order approximation for pion nucleus [5]. This might lead to a new 9. RHIC home page: http://www.rhic.bnl. production in the high momentum form of cold and dense matter. gov/. region. However, the observed result in Energy levels and the structure of 10. PHENIX home page: http://www. the high momentum region shows a hypernuclei have also been studied phenix.bnl.gov/. strong hindrance in the yield for central systematically, by using few-body 11. Most recent results can be found in the proceedings of Quark Matter Au-Au collisions. After detailed techniques with the L-S coupling taken studies, it has been concluded that the Conference, held in Jan. 2004: J. Phys. into account. G 30 (2004) S633–S1430. observed suppression in the high- For unstable nuclei, competition and momentum region is due to a creation collaboration of the shell and cluster SHOJI NAGAMIYA of dense matter in Au-Au collisions, structure have been clarified by the KEK
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Neutrino Physics
LOTHAR OBERAUER Technische Universität München
CAREN HAGNER Universität Hamburg
Introduction experiment was performed at the AGS However, connected with neutrino It was a desperate attempt to rescue in Brookhaven by Ledermann, masses is the mixing of neutrino mass energy and angular momentum Schwartz, and Steinberger (Nobel prize eigenstates, which finally leads to the conservation in beta decays when 1988) with a 15 GeV proton beam that phenomenon of neutrino oscillations. ⇔ – Wolfgang Pauli postulated the neutrino was dumped in a Be-target producing Fascinated by K0 K 0 oscillations in 1930. In his famous letter addressed pions and kaons that decay into B. Pontecorvo in 1957–58 proposed a to a meeting in Tübingen, Germany, neutrinos. In a 15t spark chamber only similar phenomenon in the lepton Pauli expressed his apprehension that charged muons were observed. Hence sector: neutrino oscillations. ν ν this new neutral and almost massless it was clear that µ differ from e. Today The present picture of neutrino particle may never get detected we know that 3 families with 3 different oscillations arises from the fact that the experimentally. Indeed it took 26 years types of neutrinos exist. An indication three flavor eigenstates ve, vµ, vτ are until F. Reines (Nobel prize 1995) and for this fact was provided by the big linear combinations of the neutrino
C. Cowan observed neutrinos via the bang theory of cosmology. Direct mass eigenstates v1, v2, v3 (with masses ν– → × inverse beta decay reaction e + p evidence for the existence of 3 neutrino m1, m2, m3). The 3 3 complex, unitary e+ + n which are emitted from the flavors was coming from the total width matrix U linking flavor and mass fission products in a nuclear power of the Z0 resonance, measured at the eigenstates is called neutrino mixing reactor. Neutrinos only interact with large electron positron collider LEP at matrix (the lepton analogon to the CKM matter via weak forces and the cross CERN, which was compared with the quark mixing matrix). Similar to the section was measured to be σ = (1.1 ± sum of all partial widths coming from quark sector this matrix can be 0.3) 10-43 cm2, which corresponds to an the Z0-decay into hadrons and charged parametrized by three mixing angles θ θ θ enormous absorption length of about leptons. The combined result from the 12, 13, 23 and one CP-violating phase δ 29 light years! In 1957 parity violation LEP data was Nν = 3.00 ± 0.06. Direct . However if neutrinos are Majorana in weak interaction was detected by C. proof was finally provided in 2000 by particles there could be two additional α α Wu and only one year later the helicity the DONUT experiment at Fermilab CP-violating phases 1 and 2 . of neutrinos by a famous experiment where the missing tau-neutrino was Neutrino oscillations occur if a performed by M. Goldhaber. He found detected unambiguously by neutrino generated with a specific the neutrino to be left handed, whereas investigating neutrinos from the τ- flavor propagates in space. It is a linear the anti-neutrino is right handed. Since decay of heavy charmed hadrons combination of mass eigenstates, each the right handed partner of the neutrino (Literature: F. Reines, Nobel Lectures of which will propagate with a slightly is missing, neutrinos are massless in the Physics 1991–1995, Ed. Gösta different frequency. At increasing standard model. If the anti-neutrino is Ekspong, World Scientific Publishing distances from the source the flavor identical to the neutrino it is called Co., 1997). content of the neutrino will change due Majorana particle. to the changing phase differences It is known that neutrinos are also From Neutrino Masses to Neutrino between the mass eigenstates. These emitted in reactions where a muon is Oscillations flavor transitions are called neutrino involved, for instance in the decay of a Today the question of neutrino oscillations. In a simplified 2 flavor π+ → µ+ + ν pion: µ. But is that neutrino masses is focused. It has a fundamental picture the probability that a neutrino ν ν α µ identical with e? The decisive impact on particle and astrophysics. of flavor and energy E, traveling a
12 Nuclear Physics News, Vol. 15, No. 1, 2005 feature article
distance L is detected as a neutrino of 70 days. The 37Ar atoms decay back via solar neutrinos. Among several flavor β is given by electron capture with a lifetime of ~50 discussed possibilities neutrino days. This decay was detected in small oscillation remained the most favorable proportional tubes. In average about 30 scenario. The chase for the smoking Ar-decays were counted after each gun of oscillation started. In where θ is the mixing angle and ∆m2 = extraction, proving the emission of Superkamiokande, an upgraded water 2 2 neutrinos in the sun. With this Cherenkov detector in Japan, the m1 – m2 is the squared mass difference of the neutrinos. Neutrino oscillation experiment the window for neutrino spectrum of high energy solar neutrinos experiments can determine the mixing astronomy has been opened. For his was measured with unprecedented angles and squared mass differences. pioneering work R. Davis was honored accuracy. However, no deviation from If neutrinos propagate in matter with the Nobel prize in 2002. the expected spectral shape was resonant amplification of the oscillations However, there remained a puzzle. detected. The break through succeeded can occur due to the different types of The measured neutrino rate was with the Canadian SNO (Sudbury matter interactions for different neutrino roughly 1/3 of the expected one. As the Neutrino Observatory) heavy water flavors. This leads to effective mixing threshold for the reaction is rather high detector situated in the underground angles, which depend on the matter (814 keV) only a small part of the mine in Sudbury. In addition to neutrino density. In current experiments these neutrinos emitted in the pp-cycle could electron scattering (es) two reactions ν 2 → 2 – matter effects play an essential role for be detected and it was argued that the can be used e + H p + e as well ν 2 → ν solar neutrinos (Literature: S. Bilenky, observed anomaly could be explained as x + H p + n + x. The former “Phenomenology of Neutrino by changing parameters of the solar charged current (cc) reaction can be ν Oscillations,” Prog. Part. Nucl. Phys. model. Although many astrophysicists triggered by e’s only, whereas the latter 43:1–86, 1999). did not believe in this “solution” further neutral current (nc) process is possible experimental data were desired. for all neutrino flavors. Therefore it is Key Experiments I: Solar Neutrinos Since ca. 1990 two radiochemical possible to investigate whether solar and Reactor Experiments experiments (GALLEX and SAGE) neutrinos change the flavor on their way using the reaction ν + 71Ga → e– + 71Ge from the sun to the earth. The The energy in the solar center is e generated by thermonuclear fusion of measured the integral electron neutrino experimental result is indeed exciting. hydrogen to helium. The sum reaction flux at an energy threshold of 233 keV, The nc-reaction rate is significantly – → 4 ν which allows comprehension of all exceeding the cc-reaction rate. From the is 4H + 2e He + 2 e and the energy released hereby is ca. 26 MeV. From branches of the solar pp-cycle. Both data one concludes that about 2/3 of the well-known solar luminosity S = experiments are in perfect agreement solar neutrinos have changed their 8.5⋅1011 MeV cm-2s-1 one may estimate and show a significant neutrino flux flavor (Figure 1). This is a direct clue Φ deficit of about 50%. In the meantime for neutrino flavor transformation and the solar neutrino flux at Earth to be ν ≈ 2S / 26 MeV ≈ 6.5⋅1010 cm-2s-1. the first direct detection of solar implies individual lepton number Quantitatively the fusion processes neutrinos with energies above ~7 MeV violation. The standard model of inside the sun are described in solar succeeded in the Kamioka mine, Japan, particle physics has to be extended. models. It is believed that in the sun via elastic neutrino electron scattering. Interesting for astrophysics is the the so-called pp-cycle is the dominating The collaboration used a water measured nc-rate, which yields the total process. In the pioneering Homestake Cherenkov detector where the direction solar neutrino flux. It is in good neutrino experiment R. Davis proved of the neutrino could be measured. agreement with the rate predicted by the the basic idea of energy generation in Again a clear deficit in the neutrino flux solar model. Hence, we can conclude the sun. Deep underground the was observed. After the GALLEX that the longstanding solar neutrino production of Ar-atoms in a 615t tank result it became evident that an puzzle is solved and neutrino flavor astrophysical solution for the solar transition has been proven. filled with perchlorethylen (C2Cl4) has been detected since 1970. They stem neutrino puzzle was excluded. On the By analyzing the possible mass and ν 37 → – 37 contrary neutrino properties beyond the mixing parameters it turned out that the from the reaction e + Cl e + Ar and were extracted from the target tank standard model of particle physics must best fit values might be probed by after an exposition of in average 60 to be responsible for the disappearance of terrestrial experiments, completely
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ν ↔ ν between e µ. (Literature: J. Bahcall and C. Pena-Garay, New Journal of Physics, 6, 2004, 63).
Key Experiments II: Atmospheric Neutrinos and Accelerator Experiments Another evidence, actually the first claim of evidence for neutrino oscillations, came from the Super- Kamiokande (SK) collaboration, who reported “Evidence for oscillation of atmospheric neutrinos” in 1998. Atmospheric neutrinos are decay Figure 1. Evidence for flavor transformation of solar neutrinos in SNO. This plot products of pions, kaons (and of the shows the cc (red), nc (blue) and elastic scattering (green) neutrino fluxes (with generated muons), which are produced σ Φ Φ in collisions of primary cosmic ray 1 errors) measured by SNO as a function of the ve-flux e and the vµτ-flux µτ. Φ = Φ Φ particles with nuclei of the upper The slope of the blue band is -1 because NC e + µτ. The blue band represents the total 8B solar neutrino flux. The dashed lines indicates the value predicted by atmosphere. Therefore the ratio R of the standard solar model. The red band is vertical because Φ Φ . The slope of muon neutrinos to electron neutrinos is CC e expected to be R = (ν– + ν )/(ν– + ν ) the green band is given by the ratio of the v and v , vτ elastic scattering cross- µ µ e e e µ ≅ 2 independent of the energy. The sections. Because all bands intersect in one point, consistent values for the ve and Φ ≅ 2 ⋅ Φ atmospheric neutrino problem had been the v τ neutrino fluxes can be derived. One finds that τ . This means that µ µ e under investigation since the 1980s by 2/3 of the v have transformed into v τ! e µ various experiments, for example, by the water Cherenkov detectors Kamioka and IMB, who reported independent from solar physics. 0.041(syst). The probability to be Rmeasured / Rtheory ≈ 0.6 and by the iron Nuclear power reactors are a very consistent with no oscillation is below calorimeters NUSEX and FREJUS who intensive source of low energy anti- 5%. On the contrary, it is now evident observed Rmeasured / Rtheory ≈ 1. electron neutrinos. Former searches for that neutrino oscillations cause the The situation became clearer after oscillations at reactors were performed flavor transition observed in solar 1996 when the 50kton water cerenkov at a distance of about 1 km at most and neutrino experiments. This implies that detector Super-Kamiokande started no hint for such an effect was found. neutrinos mix and have mass. Very operating and eventually collected However, at much further distances of recently the KamLAND collaboration enough statistics to perform a zenith ~100 km or more the effect should published new results with improved angle analysis of the observed electron appear if the flavor transition seen by statistics. Now the energy spectrum neutrino and muon neutrino events (In the solar experiments is really due to shows a significant distortion that is in the SK-I data set over 11000 events are neutrino oscillations. The Japanese excellent agreement with the spectral used in the oscillation analysis). The KamLAND experiment in the Kamioka shape expected from neutrino zenith angle is defined as the angle mine has measured reactor neutrinos at oscillation (Figure 2). between the zenith direction and the an average distance of about 180 km The currently best global fit values direction of the observed neutrino. It ∆ 2 +0.6 × -5 2 with a 1 kt liquid scintillation detector are m 12 = 8.2- 0.5 10 eV for the turned out that although the number of since the beginning of 2002. After more mass difference squared and tan2θ = downward muon events is as expected, +0.09 than one year the first result was 0.40- 0.07 for the mixing angle. This is the number of upward muon events is released. The ratio of the observed rate the so-called Large Mixing Angle less than expected. The number of to the expected one in case of no solution for the solar neutrino puzzle. electron events both upward and oscillations is r = 0.611 ± 0.085(stat) ± It describes the leading oscillations downward behaves as expected.
14 Nuclear Physics News, Vol. 15, No. 1, 2005 feature article
typical oscillation pattern: a “dip” in the oscillation probability as a function of L/E can be resolved and the exotic hypothesis of neutrino decay and decoherence can be excluded at the 3.4σ and 3.8σ level. The oscillation hypothesis for atmospheric neutrinos has been confirmed, yet with lower statistical significance, by the final analysis of the MACRO and SOUDAN2 experiments. In June 1995 K2K, the first long baseline accelerator experiment started with the goal to test the oscillation hypothesis for atmospheric neutrinos. ν A beam consisting dominantly of µ with energies around 1 GeV is produced at the KEK accelerator facility in Japan and sent over a distance of 250 km to the SK detector to count the number of surviving ν . There is also a near Figure 2. Evidence for reactor anti neutrino disappearance and spectral distortion µ detector to determine the neutrino flux from KamLAND. This plot shows the prompt event energy (≈ E – 0.8 MeV) of the v and to study neutrino interactions. If ν– candidate events. Because of various backgrounds, including a potential e one applies the oscillation hypothesis contribution from geo-neutrinos below E = 2.6 MeV, the reactor neutrino propmt with ∆m2 = 2 × 10–3eV2 and sin2 2θ oscillation analysis was performed above this value. The best fit is obtained for atm atm = 1 to a muon neutrino of 1 GeV, the ∆m2 = 8.3 × 10–5eV2 and tan2θ = 0.41. This is in excellent agreement with the 12 probability to detect a muon neutrino oscillation parameters obtained from solar neutrino experiments! A global analysis after a distance of 250km is 0.7 (see from KamLAND and solar neutrino experiments yields ∆m2 = 8.2+0 .6 × 10–5eV2 12 – 0 .5 section 2). The SK collaboration reports and tan2θ = 0.40+0 .0 9 . –0 .07 that over 5 years of measurement, they would have expected 151 muon events (no oscillation), whereas they actually Because the zenith angle of an event and Palo Verde. The sterile neutrino detected 108 events. The best fit is corresponds to the distance L of the oscillation hypothesis can be tested, obtained for an oscillation hypothesis ∆ 2 × –3 2 2 neutrino traveled between its creation because one should observe fewer with matm = 2.7 10 eV , where sin ν 2θ is assumed to be maximal. In and detection, the oscillation neutral current events for sterile than for atm ν ν addition the observed distortion in the probability of a neutrino that depends µ or τ . In addition matter effects will on L will also depend on the zenith differ for sterile neutrinos. Based on energy spectrum is also consistent with ν angle. The Super-Kamiokande zenith these facts, SK favors the τ oscillation the oscillation hypothesis. Using the ∆ 2 total number of events and the spectral angle distributions for muon events are hypothesis. The best fit values are matm × –3 2 2 θ information, the K2K collaboration in excellent agreement with the = 2.1 10 eV and sin 2 atm = 1.02 neutrino oscillation hypothesis. In and the allowed ranges at 90% C.L. are: confirms the neutrino oscillation ν → ν × –3 ∆ 2 × –3 2 hypothesis at 3.9σ. principle one could have µ e , 1.5 10 < matm < 3.4 10 eV and ν → ν ν → ν 2 θ At present there are three other long µ τ or µ sterile oscillations. sin 2 atm > 0.92. ν → ν baseline accelerator neutrino oscillation However, µ e oscillations in the Recently, SK presented an analysis required parameter range are already with a restricted data sample, experiments under construction: the excluded by the reactor neutrino containing only events with very good MINOS experiment in the U.S. and the disappearance experiments CHOOZ L/E resolution. For the first time the OPERA and ICARUS experiments in
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Europe. The physics goal of these for neutrino oscillation from solar, momentum of an emitted electron is experiments is to further improve the atmospheric, reactor and accelerator transferred to the longitudinal direction ∆ 2 2 θ precision on matm (10%) and sin 2 atm, experiments. All the experimental by the inhomogeneous magnetic field. ∆ 2 to prove the typical oscillation pattern results are fully consistent with matm No significant deviation from the ∆ 2 ≅ ∆ 2 × –3 2 ∆ 2 in L/E (MINOS) and to prove the = m23 m13 = 2 10 eV and msol expected spectrum has been found and ν ∆ 2 × –5 2 appearance of τ (OPERA, ICARUS). = m12 = 2 10 eV . However, there the quoted limits are at 2.2 eV. As we All experiments will try to improve the is another claim of evidence for know the mass differences to be much θ present limit on 13 by searching for neutrino oscillation from the LSND smaller, one can set an upper limit on ν → ν subdominant µ τ oscillations. experiment at Los Alamos, which does the sum of all flavors (i.e., ∑mν (i) < These current experiments use not fit in the simple picture of three 6.6 eV) and hence constrain the conventional neutrino beams consisting massive neutrinos. LSND reports cosmological energy density due to ν ν– → ν– dominantly of µ, with a ~1% evidence for µ e oscillation with neutrinos. ν ∆ 2 ≅ 2 background of e. The CNGS (Cern to mLSND 1eV . In order to explain this In a future experiment, KATRIN at Gran Sasso) beam has an energy above third mass difference one would have Karlsruhe, Germany, the sensitivity the τ production threshold in order to to introduce a fourth neutrino. Because should be increased by one order of ν allow the identification of τ by the number of active neutrino flavors magnitude. This is an important goal detecting τ-decays. The NuMI is measured to be 3, the fourth neutrino as the neutrino mass still has important (Fermilab to Soudan) beam is below the would have to be a so-called sterile links to the developments of large τ production threshold, because this neutrino. The goal of the MiniBooNE structures, of r-processes in lowers the backgrounds for the main experiment at Fermilab, which started Supernovae, and perhaps even with the objectives of the MINOS experiment. in 2002, is to test the LSND claim. At question of the origin of ultra high The MINOS experiment uses a near and present MiniBooNE has collected 28% energy cosmic rays. a far detector. The latter is located in of the necessary data and expects first Searches on neutrinoless double the SOUDAN mine and consists of 5.4 results in 2005. beta decays (ββ–0ν) test absolute kton magnetized iron planes interleaved neutrino masses too. Besides also the with scintillator planes. The OPERA Direct Searches for Neutrino Masses nature of neutrinos is probed. Only if detector provides a target of 1.8 ktons Although we know the neutrino neutrinos are Majorana particles, ββ– of lead-emulsion bricks. The ICARUS mass differences from neutrino 0ν decay may occur. This process detector is a liquid argon TPC. A first oscillation experiments the absolute violates Lepton number conservation. module will be installed with a target mass levels are still unknown. For Additionally a flip of the chirality is of 0.6 ktons. The distance to the far cosmology the absolute masses of necessary. This can be provided by a detectors is 730 km in all experiments. neutrinos are extremely important. If finite neutrino mass. The amplitude of 2 The far detector of MINOS is already the level for the masses would be this process is proportional to mββ = 2 2 installed and running, taking ~10 eV, neutrinos would significantly |∑Ueimi| , the squared sum of all mass atmospheric neutrino data. The NuMI contribute to the energy density of the eigenvalues weighted with the mixing neutrino beam will start by the end of universe. probabilities. There exist several gg- 2004. The CNGS neutrino beam is The most sensitive test for absolute nuclei which are candidates for ββ–0ν scheduled for 2006 and the OPERA neutrino masses comes from precise decays. Experimentally the beta detector is presently being installed at measurements of the tritium beta decay spectrum is investigated. Besides the Gran Sasso (Literature: M. C. spectrum. A finite neutrino mass would continuous spectrum due to the allowed Gonzalez-Garcia et al., Phys. Rev. D63: be detected by a deviation of the ββ–decay with emission of two 033005, 2001). spectral shape close to the endpoint. neutrinos a mono-energetic line should Today the best limits are provided by appear at the endpoint if ββ–0ν decay Open Questions and Perspectives two experiments, performed in Troitsk, occurs. The currently best limit comes Russia, and Mainz, Germany. In both from the Heidelberg-Moscow The LSND Experiment and the Question experiments a large retarding magnetic experiment, performed at the Gran- of Sterile Neutrinos solenoid is used. The spectrometer has Sasso underground laboratory in Italy There is now compelling evidence a large acceptance as the transverse with 5 Ge-detectors using in total
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76 ν 10.9 kg of enriched Ge (86%). The CHOOZ reactor neutrino experiment, τ oscillations at the given long baseline 25 ν– obtained lifetime limit T1/2 = 1.9·10 y where no disappearance of e was distance (~800km for NOVA and corresponds to a mass limit of mββ < observed at 1km from the reactor core. 295km for T2K). In addition the energy 0.35 eV (90% CL). Performing a new The size of the missing mixing angle spectrum becomes very narrow, which θ peak analysis a part of the collaboration 13 would be another important reduces the background. The detector has published evidence of a line very indicator for the correct neutrino mass for the Japanese experiment will be the close at the endpoint of 2039 eV. model and the new physics behind it. water cerenkov SK, the J-PARC facility Interpreting this line as due to ββ–0ν Therefore great efforts are presently is already under construction. The decay would imply mββ < (0.1–0.9) eV. undertaken in order to design and build NOVA detector will be a large (~50 The large uncertainty is mainly caused experiments optimized for sensitivity kton) calorimeter, with scintillator θ θ by the lack of knowledge about the on 13. One uses the fact that 13 will planes. With this experiment, neutrino nuclear matrix elements. Whether this cause small subdominant effects in the physics will be back above ground, as peak is due to new physics or simply three flavor oscillation probabilities the detector no longer requires to be an unidentified background line is not measured at L and E values, where underground due to the short beam ∆ 2 clear yet. If confirmed in future Ge- oscillations due to matm are dominant pulses. Baseline distance and neutrino experiments (GERDA in Europe, There are two oscillation channels in energies are different in the two Majorana in the USA), the effect should which one can observe these effects. experiments, which might allow to ν → ν be probed with other isotopes. One The first is µ e oscillation, where disentangle some of the degeneracies θ example is Cuoricino at Gran-Sasso, an the probability depends not only on 13, and correlations. The superbeam experiment using 42 kg of TeO2 as but also on the two mass differences, experiments will start around 2009. cryogenic detector. The candidate 130Te all mixing angles and the CP-violating Reactor experiments have been has a higher endpoint (2.6MeV), which Dirac phase δ. This offers the advantage discussed intensively in the last two is advantageous due to the larger phase that δ is in principle detectable. years, since the clean information on θ space and the lower background. Other However, correlations and degeneracies 13 would help to resolve the mentioned 136 150 projects using Xe or Nd (endpoint will require more than one experiment correlations and degeneracies. In order 3.2 MeV) are in the R&D phase. in order to disentangle the values of all to improve the CHOOZ limit, one has Generally, future projects aim to reach unknown parameters. This method will to increase statistics and to reduce the sensitivities of ~20meV for mββ be used in neutrino superbeam systematic errors to the 1% level. This (Literature: Y. Grossmann, TASI 2002 experiments. The second channel, used is possible by comparing the rates and ν– → ν– Lectures on Neutrinos, hep-ph/ by reactor experiments, is e e energy spectra of a near detector (at 0305245. H.V. Klapdor-Kleingrothaus, where the probability to measure the distances of 100–200 m) to those of a “Sixty Years of Double Beta Decay,” disappearance of anti electron neutrinos far detector (at distances 1–2 km). Both 2 θ World Scientific 2001 and NIM A, Vol. is proportional to sin 2 13 and strictly detectors should have at least 10 tons 510, No. 3, 2003, 281). independent of δ. Therefore one will of active target. The target is typically θ obtain a clean value for 13. a Gd loaded liquid scintillator providing Θ Superbeam experiments are planned high neutron detection efficiency. A 13 and CP-Violation Two of three mixing angles of the in the U.S. at Fermilab (NOVA) and in good candidate is the Double-CHOOZ neutrino mixing matrix have been Japan at the J-PARC facility (T2K). experiment at the old CHOOZ site in measured. Both are relatively large. Superbeams are produced like France, where one could use again the It should also be pointed out that the conventional neutrino beams, but the existing underground far detector site. large values of two neutrino mixing proton beam power will be much The first precision reactor experiments angles are in contrast to the strong increased (in the MW range). In both could start around 2008 and will be able hierarchy of the CKM mixing angles experiments the detectors will be to reach sensitivities of the order 2 θ in the quark sector of the standard located off-axis with respect to the sin 2 13 < 0.03. This could be further model. The only mixing angle, which beam. It turns out that by varying the improved in future larger experiments. θ off-axis angle, the average neutrino In the far future (~2015) it is remains to be determined is 13. The 2 θ energy in the beam can be tuned to the planned to increase the detector size and best limit sin 2 13 > 0.2 at 90%CL (for 2 –3 2 ν → ∆ optimal value, which maximizes µ beam intensity for the superbeam m13 = 2·10 eV ) was obtained in the
Vol. 15, No. 1, 2005, Nuclear Physics News 17 feature article
experiments. This second generation of recorded in two large water Cherenkov cosmic microwave background (CMB). superbeam experiments will have the detectors (Kamioka, Japan, and IBM, Up to now this extreme low energy goal to determine the CP-violating USA) within a time window of about neutrino flux could not be detected. Big Dirac phase, which is however only 20 seconds. This observation allowed bang nucleosynthesis sets limits on the θ possible if the size of 13 is not too us to measure for the first time the number of neutrino flavors and neutrino small. The priority for the present energy release of a gravitational masses. Even better limits are coming generation of experiments is therefore collapse, as about 99% of the total from recent redshift surveys and θ to determine 13. gravitational energy is emitted in measurements of the CMB. The The ultimate high energy neutrino neutrinos. In spite of the small number reported limits on the neutrino mass are source could be a neutrino factory of events the basic idea about the somehow model dependent and are in ν ν providing pure e, µ (and anti neutrino) mechanism of a supernova of this the range between 0.7 eV and 1.8 eV. It beams. Recently the concept of so- nature (i.e., SN type II) was confirmed. is amazing that this cosmological limits called beta beams became very With running detectors, like Super are in the same range as laboratory attractive and feasibility studies are Kamiokande, a supernova type II constraints or even slightly better. On under way. Radioactive ions (good explosion in our galaxy would be the other side neutrino oscillations set candidates are 6He and 18Ne), which can accompanied by a neutrino signal of a lower limit on the neutrino mass. β+ β- ν decay in or mode and thus emit e about 15,000 events within ~20 Therefore we know that neutrinos ν– and e, are accelerated to energies seconds. Hence, the development of a contribute to the mass density of the around 150 GeV/nucleon. They are gravitational collapse could be followed universe. They are the first detected hot Ω then stored in bunches in a storage ring. in great detail. In order to measure dark matter particles. Their density ν The novel features of these beams are flavor dependent fluxes different nuclei in unit of the critical density is restricted Ω that they contain exactly one flavor, the as target for neutrino are proposed. In to 0.001< ν < 0.04. energy spectrum is very well known LENA (Low Energy neutrino Geophysical neutrinos may tell us and the collimation is very good. Astronomy) a large liquid scintillator about the concentrations of U, Th, and Possible sites include CERN, GSI, and detector is proposed to serve as detector K in the Earth. The contribution of GANIL (Literature: P. Huber et al., for supernova neutrinos. Here neutrino terrestrial radioactivity to the energy “Prospects of accelerator and reactor interactions on protons as well as on flux from the Earth (in total about 30 neutrino oscillation experiments for the 12C could be used that would allow us TW) is still unknown. With large liquid coming ten years,” hep-ph/0403068). to disentangle the flavor composition scintillation detectors like KamLAND, of a supernova burst in time and energy. Borexino, and LENA the U- and Th- Neutrinos in Astrophysics and From all past supernova type II concentrations could be measured at Cosmology explosions in our universe one expects different sites. Therefore it could be Solar neutrino physics opened the a low background of relic supernova possible to disentangle the window to astrophysical observations neutrinos. Up to now only upper limits contributions from the continental and where neutrinos are used as probes. on the flux of those SNR-neutrinos are oceanic crusts. With LENA is should Indeed the basic idea of thermal nuclear reported. In LENA or in a modified be even possible to determine the fusion as source for stellar energies was SuperKamiokande detector (Gd-loaded concentrations in the mantle of the proven by detecting solar neutrinos and water) the detection of SNR-ν’s could Earth. in future important details about the pp- succeed and would tell us details about Some geophysicists believe that a and the CNO-cycle may be revealed by star formation in the early universe. gigantic natural nuclear reactor at the new experiments in this field. The first Neutrinos should have been emitted center of the Earth provides the energy neutrino signal outside of our solar in an enormous number in the big bang. for the Earth’s magnetic field. This system, even outside from our galaxy After ~1 second neutrinos decoupled appearing wild hypothesis can be tested was observed in February 1987 when a from matter and since then they are free by a future low energy neutrino detector blue giant star in the Large Magellanic streaming in the universe. Due to the as proposed e.g. in LENA. Cloud exploded as a supernova at a expansion of the universe they are red- High energy neutrinos may act as distance of about 50 kpc (ca. 150 light shifted and their mean temperature probes from astrophysical objects like years). In total 19 neutrino events were should be 1.95 K, a little lower as the supernova remnants, binary systems,
18 Nuclear Physics News, Vol. 15, No. 1, 2005 feature article
active galactic nuclei, and quasars. The atmosphere should be observed. The in the recent past with the discovery of neutrino source could be high energy former is detected by a large number neutrino oscillation. The window to pions and kaons which decay in flight. of water Cherenkov detectors, the latter neutrino mass and mixing is open! The Large Cherenkov detectors under water by phototubes in the form of a fly’s eye. first precision measurements of mass and in ice are going to be constructed In total 2 arrays with 3000 km2 area differences and mixing angles have to detect those neutrinos. At the south each should be covered. The second started and many will follow. But pole the Amanda detector is already array should be constructed in the although many of the neutrino taking data and the 1 km3 large Icecube northern hemisphere to cover the whole parameters are now known, some still project is under way. High energy sky. With Auger even events with have to be determined until our picture neutrinos are detected via charged energies above ~1020 eV will be of the neutrino sector is complete. The current interactions by measuring the detected. The full deployment in most important questions are: What is generated charged leptons. As there is Argentina is expected for the year 2005 the mass of the lightest neutrino and a large background from atmospheric (Literature: L. Oberauer, Modern what is the mass hierarchy? Are muons only upgoing particles can be Physics Letters A, Vol. 19, No. 5, 2004, neutrinos Majorana particles? What is θ used as neutrino candidates. Hence, 1–12. T. Gaisser, F. Halzen and T. the value of 13? Is there CP-violation Amanada and Icecube will probe the Stanev, “Particle Astrophysics with in the lepton sector? Although there is northern hemispere of the sky for point High Energy Neutrinos,” Phys. Rept. hope that these questions might be like neutrino sources. In order to cover 258:173–236, 1995). answered with the present or next also the southern part a large generation of experiments, for some of underwater detector is discussed Conclusion and Outlook them it might take decades again. for the Mediterranean Sea. Three In 2005 we will celebrate the 75th On the other hand detector collaborations (Antares, Nestor, Nemo) anniversary of Paulis neutrino postulate technology and our knowledge of are exploring the best site for the final in Tübingen. Since then neutrino neutrinos have already so much experiment that should start taking data physics has evolved into a key domain improved that it is now possible to use at about 2008. High energy cosmic of particle physics, where we expect to neutrinos as probes, for example, in neutrinos may also generate air find hints leading to new physics at high astrophysics. Therefore in the next showers. In the Auger experiment in energy scales and grand unification. In years we are awaiting many interesting Mendoza, Argentina, the air shower as 75 years impressive experimental and maybe surprising results from well as fluorescence of N2 in the results have been achieved, culminating neutrino physics.
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To make the Nuclear Physics News calendar even more useful it is now being put on the Web and is expanded to include other nuclear physics events than just conferences. Many of us have had two different meetings to attend at the same time: the first step toward avoiding this is to have information easily available on what is going on in our community. To achieve this, please help us to keep the calendar updated: make sure that all conferences, all collaborations, and all laboratories send information to us.
KARSTEN RIISAGER, Aarhus University GABRIELE – ELISABETH KÖRNER, NuPECC
Vol. 15, No. 1, 2005, Nuclear Physics News 19 feature article
Structural Evolution in Nuclei: The Rich Structures of a Simple Hamiltonian
J. JOLIE Institute for Nuclear Physics, University of Cologne, Zulpicher Str. 77, D-50937 Cologne, Germany
R. F. CASTEN Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520, USA
Introduction that scale as the d–boson number. It H = aHsph – bHdef (1) One of the most interesting therefore gives a set of equally spaced developments in low energy nuclear It is of Ising form, exhibiting a solutions corresponding to a spherical structure in recent years is a new competition between equilibrium vibrator; the second term, which is a perspective on structural and shape configurations of two different quadrupole interaction between bosons, evolution, as a function of N and Z. symmetries: the first term is spherical mixes the s and d boson basis states of Much of this renewed interest has driving, the second deformation the IBA, and yields deformed solutions. been generated by discoveries of driving. For small b/a the equilibrium The equilibrium shape is spherical for phase transitional behavior at low solution is spherical, but a deformed η values ranging down from unity, energies in finite nuclei and the configuration can co-exist at higher crosses from spherical to deformed at η ≡ η proposal and validation of the idea energies (see Figure 1, curves 1, 2). As some value of crit, and is deformed η η of critical point symmetries. Beyond b/a grows, the deformed solution for < crit. The form of the quadrupole this, the subject embraces the concepts descends in energy and, for some b/a operator introduces another parameter of dynamical symmetries, Landau (curve 3 in Figure 1), crosses the χ, which is related to axial asymmetry, theory, a new mapping of structural spherical one to become the ground and which notably increases the trajectories for a wide variety of state. This is the first order phase richness of the structures possible with nuclei, and order and chaos in nuclear transition where the deformation, β, spectra. In this short overview, we will jumps discontinuously from 0 to finite focus on even–even nuclei although β. Thereafter, for larger b/a, the fascinating applications to odd–even equilibrium solution remains deformed nuclei, exploiting the concept of (curves 4, 5). nuclear supersymmetry, have recently We can write a Hamiltonian like that been made. We will frame our of Eq. (1) in the context of the IBA discussion in the context of the rich model [2] using the simple Consistent structures of a simple Hamiltonian of Q Formalism as follows Ising form [1]. 1–η ˆ α ηˆ ˆ ˆ H = ( nd – QχQχ ) (2) Collective Structures and N Structural Evolution where N is the boson number. Here we Figure 1. Energy surfaces of a We will focus our discussion on have used η to play the role of a/b and sequence of nuclei evolving from collective nuclei, which can have a pulled out an overall energy scaling spherical to deformed in a first order range of structures from spherical to factor α. Eq. (2) is written so that the phase transition with changes in deformed (axially symmetric, prolate or full range of structure is described by nucleon number. Curve 3 corresponds oblate, or with various degrees of γ- η values in the range of 0 to 1. The first to the phase transition where the softness). Consider the following term is diagonal in the number of s and equilibrium value of the deformation, β schematic Hamiltonian d bosons of the IBA, and gives energies , changes discontinuously.
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χ ∈ β γ Eq. (1). The parameter [- 7/2, each dynamical symmetry. These of 0 and 0. If such a minimum occurs χ β 7/2]: = - 7/2 (+ 7/2) corresponds symmetries have been discussed earlier at 0 = 0 one has the higher (spherical) η η β ≠ (if < crit) to a prolate (oblate) axially in NPNI [3]. One notices that, although symmetry and for 0 0, the lower symmetric rotor and χ = 0 to a the number of parameters is reduced to (deformed) symmetry. A, B, C . . . are completely γ-soft rotor. two, the Hamiltonian contains the rich parametric functions of some control In order to visualize this simple group structure of the IBM. variables. In classic Landau theory, they parameterization the Casten triangle is To understand the evolution of are often pressure and temperature. In used in which any position is defined structure with (η, χ) it is useful to turn the nuclear case, they would depend, by η and χ. Such a triangle is shown in to the classic Landau theory [4] of phase for example, on the number of Figure 2. The great interest of the transitions. This will also allow a nucleons, the orbits they occupy, and simple Hamiltonian of Eq. (2) lies in generalization of the triangle [5]. To do the interactions of these nucleons, the fact that it can be used to locate most this, we note that the IBA Hamiltonian which we parameterize in terms of η nuclei in the triangle and that one can of Eq. (2) can be written in terms of the and χ. visualize the general six-dimensional shape variables β and γ, using an We now present a simplified IBM Hamiltonian in a two-dimensional approach called the coherent state analysis, which largely ignores the image. Moreover the triangle is formalism. The details are not parameter γ, because its influence is constructed such that the three corners important: the main point is that the trivial. We keep terms up through the are formed by the three dynamical energy surface can be written as an β4 term in Eq. (3). The equilibrium η γ o limits of the IBM: U(5) ( = 1), O(6) expansion of the nuclear energy values are either 0 = 0 when B < 0, or η χ η χ β γ o ( = 0, = 0), SU(3) ( = 0, = functional in powers of : 0 = 60 when B > 0. The linear
- 7/2). These limits describe vibra- dependence on B then allows one to tional, γ-unstable, and prolate deformed Φ Φ β2 β3 γ β4 β5 absorb the influence on γ in the sign of = 0+A +B cos3 +C +O( ) (3) nuclei. Figure 2 contains mini level B. This analysis, although over- schemes illustrating some key Φ simplified, captures the essence of the where 0 corresponds to a spherical observables showing the characteristic solution. Equilibrium conditions occur physics. level and transition rate patterns for when Φ is a minimum for some value(s) For any stable equilibrium state, the first derivative of Φ with respect to β must be zero and the second derivative positive. Thus, one obtains:
β(2A+3Bβcos3γ +4Cβ2) = 0 (4) and 2A+6Bβcos3γ +12Cβ2 > 0 (5)
First of all, C should be positive to get finite solutions. This gives two solutions. One is the spherical solution β ( 0 = 0), which, from Eq. (5), implies A > 0. This is reasonable. The spherical β equilibrium solution of Eq. (3) ( 0 = 0) is only possible if Φ has a minima at β = 0 that requires A > 0. The second β ≠ Figure 2. Symmetry triangle of the IBA model. The dynamical symmetries are solution corresponds to 0 0. This indicated at the vertices, along with mini-level schemes showing their solution is obtained by solving the characteristic properties. The numbers on the transition arrows are relative B(E2) quadratic in Eq. (4). For the moment, values in the limit of large N. The physical meaning of the parameters η and χ in consider the case where B = 0 in Eq. defining positions within the triangle are also identified. (3) (a line in A - C parameter space).
Vol. 15, No. 1, 2005, Nuclear Physics News 21 feature article
This is illustrated in Figure 3 (left). or B = 0, each corresponds to a curve in former, R4/2 increases from 2.0 to 3.33 Then, trivially, / the phase diagram. These two first order and the phase transition corresponds to 72 phase transition trajectories meet at an the point (ηvalue) of sharpest increase –A β = ± (6) isolated second order phase transition, (maximum of dR /dη). This feature 0 2C 4/2 defined by the point A = 0, B = 0, which immediately discloses an important β is a nuclear triple point. Figure 3 (right) aspect of structural evolution in the For finite and real 0 this requires A and C to be of opposite sign. Since, for takes these ideas and now casts them triangle with the Hamiltonian of Eq. (2), small β, the β2 term dominates, one has in the context of an extended symmetry namely, the highly nonlinear way in a deformed minima only when Φ in Eq. triangle [5]. Here U(5) corresponds to which structure changes en route from (3) initially decreases as β increases the spherical solution, and the diagonal the U(5) vertex to the deformed SU(3)- from zero, which requires A < 0. The line from a point on the U(5)-SU(3) leg O(6)-SU(3) leg. We will see this feature minimum is produced when the β4 term to a point on the U(5)-SU(3) leg is the later in our discussion of order and dominates. first order spherical-deformed chaos. It implies, for example, that well-
Thus, we see that the nuclear phase transition line. The line from O(6) down deformed nuclei (with, say, R4/2~3.31) diagram has three phases, spherical to this line is the prolate–oblate actually appear quite far from the SU(3) β β transition line. Nuclei on opposite sides vertex. ( 0 = 0), prolate ( 0 > 0), and oblate β of these two lines have different Along the SU(3)-O(6)-SU(3) ( 0 < 0). The spherical–deformed phase + transition occurs when A changes from equilibrium phases (symmetries). transition region in Figure 4, Q(2 1) positive to negative, that is, at A = 0. Where these two lines meet is the changes from negative (prolate) to Spectra corresponding to simple isolated triple point of second order positive (oblate) at O(6). Here, the models of these cases have been phase transition. critical point of the phase transition is discussed recently in NPNI [6]. The It is interesting to study how the coincident with O(6) and marks the + prolate–oblate phase transition occurs solutions given by the Hamiltonian of point where Q(2 1) changes sign and + when B changes from negative to Eq. (2) behave across these first order Q(2 1) /d|χ| peaks. phase transitions. To do so we look at For both transition regions, Figure positive, that is, it occurs at B = 0 (and the characteristic observable R and 4 shows the behavior for two boson A < 0, C > 0). As illustrated in Figure 3 4/2 (left), if we think in terms of a η, χ show, in Figure 4, predictions along the numbers 10 and 20, showing that the phase diagram analogous to the P, T U(5) → SU(3) transition region and of phase transition increases in sharpness + diagram of Landau theory, then the first Q(2 1 ) along the SU(3)-O(6)-SU(3) with increasing N, as expected for a prolate–oblate transition region. In the classical phase transition [5]. Finally, order phase transition conditions, A = 0 Figure 4 includes examples of the empirical behavior for each of these transitions (Sm isotopes for U(5)- SU(3), and Hf-Hg isotopes for the prolate–oblate case). The behavior nicely mimics the calculations. (Detailed comparisons are shown in the original literature [7].) Although data for a prolate-oblate case are scarce and do not reach fruition on the oblate side because of the impending double shell 208 Figure 3. Landau analysis of nuclear phase transitions. On the left is a simplified closure at Pb, there is a moderate + representation of the phases and first order phase transition lines corresponding increase in Q(2 1) going from Pt to Hg. Clearly, a fascinating quest in exotic to A = 0 and B = 0 in Eq. (3). The axes are labeled by the traditional variables P, T but would stand for the corresponding nuclear parameters in the present nuclei would be to search for a full discussion. The right side shows the application of this analysis to the equilibrium prolate–oblate transition region. With phases of nuclei, including the extension to oblate shapes. The symbol “t” denotes the altered single particle level a nuclear triple point where two lines of first order phase transition meet. sequences thought possible in weakly
22 Nuclear Physics News, Vol. 15, No. 1, 2005 feature article
discussion (A few additional W and Os nuclei were also fit but are not included in Figure 5). This new mapping is quite different (primarily on account of the excellent fits to the 0+ states) than previous ones and it gives a new perspective on structural evolution. There are three key aspects of this. First, that evolution is more complex, and Z-dependent, than heretofore thought. Second, more rare- earth nuclei now occupy interior positions in the triangle. Third, the new mapping sheds insight into regularity and chaos in spectra of collective nuclei. We now turn to this topic.
Chaos and Regularity Figure 4. Behavior of observables across the two first order phase transitions The existence of regular (integrable) discussed in the text, the spherical–deformed phase transition and the prolate– and chaotic behavior in many-body oblate/ phase transition. Top: Calculated values of R as a function of η for 721 4/2 + systems forms a major theme in many χ = -7/2 for the spherical–deformed phase transition (left) and Q(2 1) as a function branches of physics. Atomic nuclei of χ for η = 0 for the prolate–oblate phase transition (right). In the latter case provide an important testing ground for χ = 0 corresponds to the phase transition (analogous to B = 0 in the discussion of such behavior because of the variety of Landau theory in the text) and to the dynamical symmetry O(6) as well. The structures they exhibit and the calculations are performed for N = 10 (full line) and N = 20 (dashed line). The + dependence of these structures on the lower part shows experimental data on R for the Sm region and Q(2 1) in the 4/2 number of constituent nucleons. Hf–Hg region and the line gives the theoretical values corresponding to the boson Chaotic behavior in nuclei is usually number N, and the fitted η and χ values [7], together with a constant effective thought of in terms of high-temperature charge of 0.15 e.b. systems where shell structure melts. However, a decade ago [9] Alhassid and Whelan carried out an important study of the chaotic behavior in nuclei at zero bound very neutron rich nuclei, there O(6) leg) to 60° (along the U(5)-SU(3) temperature using the Hamiltonian of are grounds for speculating that regions leg). By fitting the key observables in Eq. (2). As expected, they found that of deformation might be more compact any given nucleus, it is therefore the level spectra are regular at and near in N and Z and more prolate-oblate possible to position it in the triangle. the three dynamical symmetries U(5), symmetric. Such a mapping has recently been re- SU(3), and O(6) of the model and that There is much of interest in the done, requiring that not only the chaotic behavior develops rapidly as triangle and the Hamiltonian of Eq. (2) properties of the ground and γ bands one moves away from the symmetries. besides phase transitional behavior. In be fit, as has normally been the case, There were two exceptions to this particular, the two parameters, η and but those of the 0+ band as well. In all, behavior. The first, which is well χ, permit an explicit mapping of any about 50 nuclei were included in this known, happens between U(5) and O(6) nucleus onto the triangle (see Figure 2). new mapping [8]. Their locations in the and is connected to the conserved O(5) η is a radius vector from U(5) toward triangle are shown in Figure 5 (left), symmetry. The most fascinating result, the SU(3)-O(6)-SU(3) side whereas χ where, for the purposes of later however, was that there is an is an angle ranging from 0° (along the discussion, we have re-oriented it to be unexpected (“surprising” to use their U(5)-SU(3) leg) to 30° (along the U(5)- consistent with the literature and later word) region of nearly regular behavior
Vol. 15, No. 1, 2005, Nuclear Physics News 23 feature article
Figure 5. Left: Location of rare earth nuclei in the symmetry triangle. Note that to be consistent with the literature [9,10] the triangle has been flipped and rotated so that U(5) is at the top. Middle: The arc of regularity in the triangle and the location + + of the 12 nuclei identified as lying close to it. Right: Locus of near degeneracy of the 02 and 22 levels in the triangle. connecting SU(3) to U(5) along an ~3.3), and to transitional nuclei in the quantum numbers remain valid (e.g., interior arc in the triangle which can W, Os region. the phonon-like quantum numbers of be approximately parameterized by the Regular and chaotic behavior were O(5) along the U(5)-O(6) leg of the relation: distinguishable in the Alhassid–Whelan triangle). Thus, there can be level 72/ analysis by the distribution of nearest crossings and Poisson distributions of 7 η χ = (η–1) – (7) neighbor spacings of states in the same spacings result (high probability of 2 2 spin. Chaotic behavior is associated close lying levels). This is illustrated In the (η, χ) plane the location of the with the loss of good quantum numbers in Figure 6, where the spectra of 0+ regular region is independent of the (except angular momentum) and hence states are plotted for a typical value of η χ angular momentum for low to moderate of level mixing and avoided crossings. = 0.6, as a function of for N = 25. values, and of the number of valence This leads to level repulsion and a For this situation, the regular region, nucleons (i.e., the boson number N). Wigner distribution of level spacings. where ~90% of all trajectories are χ Figure 5 (middle) shows the location In regular systems, one or more regular, is centered at ~ –0.83. It is of the nearly regular region in the Casten triangle. At that time of their work, unfortunately, there were no identified nuclei corresponding to this new regular region and this finding therefore remained merely a fascinating theoretical curiosity. However, the recent re-mapping of nuclei in the rare earth region radically changes this conclusion. This is the third key aspect of the new mapping alluded to earlier. In fact, 12 rare earth nuclei were found to fall very near the regular region [10]. Figure 5 (middle) includes the location in the symmetry triangle of these 12 nuclei. Note that they span a wide variety of structures, indicated by the + bounding R4/2 values, ranging from an Figure 6. Energies of 0 states calculated with the Hamiltonian of Eq. (2) for 156 η χ anharmonic vibrator nucleus Er (R4/2 = 0.6 as a function of . The regular region, according to Eq. (7), is close to ~ 2.3) to near perfect rotor nuclei (R χ 4/2 = –0.83 and is indicated by a dashed vertical line [11].
24 Nuclear Physics News, Vol. 15, No. 1, 2005 feature article
clear that, rather suddenly, the avoided may be approximately valid in the chaotic spectra. Finally, we discussed crossings that appear for χ ≠ –0.8 values regular region. a unique empirical signature of this are replaced by nearly real crossings regular behavior. near χ ~ –0.8, as also occurs near χ ~ 0 Conclusion due to the O(5) symmetry. In this review of new topics in the Acknowledgments The question arises what are the evolution of nuclear equilibrium We acknowledge P. Cejnar, essential distinguishing features of shapes, we have traced a path linking a S. Heinze, A. Linnemann, E. A. nuclei in or near the regular region? The number of seemingly diverse but McCutchan, P. Van Isacker, P. von most characteristic and, indeed, unique, intimately connected ideas. We studied Brentano, V. Werner, and N. V. Zamfir + is the close spacing between the 22 state the rich structures of a simple with whom parts of the work presented + and the 02 state [10]. This applies Hamiltonian of 2-parameter Ising type, here were done. We also thank the regardless of the structure. Note that including dynamical symmetries, phase cafeteria in the Köln Mensa where this condition sometimes refers to states transitions, and regular and chaotic much of this work was discussed and of different intrinsic structure but in behavior. We have explained using developed. This work was supported by other cases to members of the same Landau theory why the IBM exhibits the BMBF under Project number 06 K rotational band or phonon multiplet. an isolated second-order phase 167, and US DOE Grant No. DE-FG02- In the context of the commonly used transition and continuous lines of first- 91ER-40609. 2-parameter Hamiltonian of Eq. (2), order phase transitions. We stress that, which accounts quite well for structure although we have used the IBM, all References throughout the nuclear chart, the near these results are quite general for any 1. E. Ising, Z. Phys., 31, 253 (1925). + + degeneracy of the 22 and 02 states is, collective model where the potential 2. F. Iachello and A. Arima, The in fact, a unique indicator of the regular can be expanded in powers of β as in Interacting Boson Model (Cambridge region and is its most obvious Eq. (3). Moreover, it shows how the University Press, Cambridge, England, characteristic. Indeed, as shown in theoretical framework of Landau theory 1987). Figure 5 (right), the locus of the regular 3. F. Iachello, Nucl. Phys. News is quite universal, applicable to systems International, 2, No. 3,22 (1992). region in the triangle and the locus of as diverse as nematic liquid crystals and 4. L. Landau, Phys. Z. Sowjet., 11, + + near degeneracy of the 02 and 22 states atomic nuclei. 26(1937); 11, 545 (1937); reprinted in are almost identical. We note that the This study relates to recent Collected Papers of L. D. Landau regular region does not correspond to proposals of phase transitional (Pergamon, Oxford, 1965), p. 193. an exact degeneracy but to close lying behavior, critical points and critical 5. J. Jolie et al., Phys. Rev. Lett., 89, 2+ and 0+ states and that, in the region point symmetries along the U(5)-SU(3) 182502 (2002); Phys. Rev. Lett., 87, 2 2 162501 (2001), P. Cejnar et al., Phys. of the triangle where the 12 nuclei are and U(5)-O(6) legs of the triangle. The Rev., C68, 034326 (2003). located, this energy difference is expanded triangle from the Landau 6. F. Iachello, Nucl. Phys. News slightly positive. analysis allows the definition of a International, 12, No. 3, 17 (2002). We also stress that, with Eq. (2), no nuclear triple point and symmetrizes the 7. J. Jolie, A. Linnemann, Phys. Rev. C, other region of the triangle shows this triangle with respect to oblate 031301(R) (2003); O. Scholten, F. degeneracy. Therefore, identification of deformations. Its application to the Hf- Iachello, and A. Arima, Ann. Phys. + + (N.Y.), 115, 325 (1978). nearly degenerate 02 and 22 states can Hg nuclei provides a new perspective 8. E. A. McCutchan, N. V. Zamfir and be used to identify collective nuclei on the evolution of nuclear structure in near the regular region. This kind of R. F. Casten, Phys. Rev., C69, 064306 this mass region. Applying this (2004); E. A. McCutchan, N. V. Zamfir, degeneracy of states belonging to two Hamiltonian to real nuclei we discussed submitted to Phys. Rev. C. different spin classes is, in fact, typical a recent new mapping of structural 9. Y. Alhassid and N. Whelan, Phys. Rev. of dynamical symmetries such as U(5) evolution in the rare earth region and Lett., 67, 816 (1991). or SU(3) and therefore may provide explained how this mapping reveals the 10. J. Jolie et al., Phys. Rev. Lett., 93, clues as to the (currently unknown) surprising existence of a set of nuclei 132501 (2004). nature of the underlying quantum with regular behavior lying adjacent (in 11. S. Heinze et al., to be publ. number(s) and possible symmetry that η, χ parameter space) to nuclei with
Vol. 15, No. 1, 2005, Nuclear Physics News 25 facilities and methods
Application of Low Energy Spin Polarized Radioactive Ion Beams in Condensed Matter Research
Introduction The new ISAC facility at TRIUMF (Canada), produces some of the world’s most intense radioactive ion beams (RIBs). Although the primary scientific motivation for these facilities lies in nuclear physics and nuclear astrophysics, RIBs also have applications in condensed matter (CM). Many pioneering CM experiments have already been performed at the ISOLDE facility (CERN). Continuing on this path at ISAC we have recently polarized a beam of 8Li+ to be used as a magnetic probe of ultra-thin films and interfaces. We report here on progress Figure 1. (a) A schematic of a β-NMR experiment. The initial polarization can in developing this new application of either be perpendicular to the beam direction or parallel as shown here. Plastic low energy RIBs, which is based on the scintillation detectors (F and B) are used to monitor the β-decay asymmetry as a β technique of -detected nuclear function either of (b) RF frequency with a continuous beam or (c) time with a β magnetic resonance ( -NMR). pulsed beam. The two different curves in (b) and (c) correspond to two different Conventional NMR is a powerful beam helicities. technique for probing the local electric/ magnetic properties of materials [1] However, NMR typically requires a large number (1018) of nuclear spins to isotopes with unprecedented sensitivity scientific applications are similar to generate a signal. Consequently it is [4,5] For example, in semiconductors what is now possible with low energy most widely used in studies of bulk a radioactive nucleus is ideally suited muon beams [8]. However, the positive materials. A much greater sensitivity to characterizing the behavior of an muon and a radioactive nucleus are very can be obtained with β-NMR where the isolated impurity where conventional different probes and thus provide signal is detected through the β-decay NMR lacks the required sensitivity [6]. complementary information [9]. In of a polarized radioactive nucleus. For Intense low energy beams of highly addition RIBs from an ISOL target are example, in the case of 8Li, which has polarized ions, now available at ISAC, naturally created at low energy and can a mean lifetime of 1.2 s, an energetic present new opportunities in condensed be orders of magnitude more intense electron is emitted preferentially in the matter research. In particular, because than a low energy muon beam. direction opposite to the nuclear only about 107 spins are needed to β-NMR has close similarities to polarization. Such β-decay anisotropy generate a β-NMR signal, the method both muon spin rotation and was first used to demonstrate parity is well suited for studies of nano- conventional NMR. The two basic violation in weak interactions in 1957 structures and ultra-thin films where observables are the spin precession [2]. Since then β-NMR has been used there are few host nuclear spins. frequency and spin relaxation rate, both extensively to measure nuclear Furthermore, with the unique polarized of which are used to monitor the local moments of unstable isotopes. In ion beam now at ISAC, it is possible to electronic/magnetic environment. A condensed matter β-NMR allows one vary the mean depth of implantation on schematic of a typical β-NMR setup is to simulate the behavior of stable a lengthscale of nanometers. The shown in Figure 1a. Similar to muon
26 Nuclear Physics News, Vol. 15, No. 1, 2005 facilities and methods
spin rotation, the experiment is carried However, studies with muons have to produce the radioactive ions. A wide out by implanting spin polarized shown that the temperature dependence variety of isotopes are released from the particles (ions) into the sample. A static and magnetic field dependence of the surface ionization source heated to o external magnetic field (H0) is applied frequency shifts and spin relaxation 2000 C but alkalis are preferentially along the initial spin polarization rates are often the same as those ionized because of their low ionization direction zˆ while an oscillating detected using the host nuclear spins. energy. The resulting positive ions are ν transverse magnetic field (H1 cos 2Z t) Recently we have also performed then accelerated to 30 keV forming a is stepped through a range of the first zero field β-NQR (Nuclear low emittance beam with an energy frequencies around the Larmor Quadrupole Resonance) experiment, spread of 1–2 eV. The beam is then ν γ frequency of the nucleus ( L= B), which is done in the absence of a static passed through a high resolution mass where B is the local magnetic field at magnetic field (H0=0). It is well known spectrometer so that only the isotope the nuclear site and γ is the that if a nucleus with an electric of interest reaches the experimental gyromagnetic ratio. The time averaged quadrupole moment, such as 8Li , rests area. β nuclear polarization Pz, is directly in a crystalline site with non-cubic Although any -emitting nucleus proportional to the β-decay asymmetry: symmetry, there will be a quadrupolar with non-zero spin can be studied with splitting of the nuclear spin levels even β-NMR, the number of isotopes in zero external magnetic field. One can suitable as a probe in condensed matter (1) induce transitions between these levels is much smaller. The most essential
with the oscillating magnetic field (H1), requirements are: (1) a high production and thereby alter the nuclear spin efficiency, (2) a method to efficiently where F(ν) and B(ν) are the number of population. The ability to perform polarize the nuclear spins, and (3) a counts in the F and B detectors at magnetic resonance in zero applied high β-decay asymmetry. Other frequency ν (corrected for the slightly field has important applications for desirable features are: (4) low mass different efficiencies of the detectors). studies on exotic magnetism and to reduce radiation damage on The proportionality constant A ≈ 0.15 superconductivity. It is also remarkable implantation, (5) a small value of spin depends on the beam polarization, β- that the 8Li NQR resonances are narrow so that the βNMR spectra are relatively decay characteristics, and various (few kHz) and easily observed at simple, and (6) a radioactive lifetime instrumental parameters. The acoustic frequencies. Recall that in that is not much longer than a few resonances are detected by measuring conventional NQR the signal to noise seconds. Table 1 gives a short list of the β-decay asymmetry as a function ratio degrades rapidly with decreasing the isotopes we have identified as ν ν frequency, and has a practical lower suitable for development at ISAC of . A decrease in Pz occurs when is matched to the nuclear spin splitting limit of a few MHz. where production rates of 106/s are subject to the usual magnetic dipole The β-NMR and β-NQR results easily attainable. Our initial efforts have selection rule δm = ± 1 (see Figure 1b). from ISAC demonstrate that a low focused on 8Li (I = 2), which is the The position of the β-NMR resonance energy polarized beam of 8Li can be lightest suitable isotope for β-NMR. is a precise measure of the local used as a sensitive probe of the The low mass means that the implanted magnetic field at the site of the nucleus magnetic properties of thin films and 8Li rests at crystalline sites away from which depends on the local electronic interfaces where it is very difficult to any radiation damage. Also the mean structure and static spin susceptibility obtain equivalent information with lifetime (1.2s) is comparable to typical of those electrons. Alternatively one can conventional NMR. Although the range nuclear spin relaxation times in many straggling for such ions is large (of the materials. In addition, both the measure the 1/T1 nuclear spin relaxation rate by implanting a short beam pulse order of the range) the average depth gyromagnetic ratio (γ = 6.3 MHz/T) and and measuring the time evolution of the can be controlled very precisely in the electric quadrupole moment of 8Li (Q polarization (see Figure 1c). The spin 5–200 nm range. = +33 mB) are small so that hyperfine relaxation rate is sensitive to the interactions with the crystal electron spin dynamics. Of course in β-NMR Probes at ISAC environment are weak. For example, in general the presence of the impurity At the TRIUMF ISAC facility the metals we expect small metallic will alter the local electronic structure. primary 500 MeV proton beam is used frequency shifts in the 100 ppm range;
Vol. 15, No. 1, 2005, Nuclear Physics News 27 facilities and methods
Table 1. Examples of isotopes suitable for β-NMR. The production rates are spin polarization is achieved. The final projections except in the case of 8Li. step is to strip off the valence electron by passing it through a He gas cell [11]. Isotope Spin T γ Maximum β-Decay Production 1/2 8 + (s) (MHz/T) Asymmetry rate (s–1) The polarized Li beam can then be guided electrostatically to one of the 8Li 2 0.8 6.26 0.33 108 spectrometers without affecting the 11Be 1/2 13.8 22 0.33 107 nuclear spin polarization. Typically the 15 8 O 1/2 122 10.8 0.7 10 polarization of the beam is about 70% 17Ne 1/2 0.1 0.33 106 and very stable on the time scale of a measurement. The spectrometers are positioned so that the polarization whereas, the electric quadrupolar a fast collinear optical pumping direction is parallel to the high field splittings at non-cubic sites should be method, which is well-established for spectrometer and transverse to the axis only 10s of kHz. Thus, with narrow the case of alkalis. A schematic of the of the beam entering the β-NQR resonances and relaxation rates slow polarizer at ISAC is shown in Figure 2. spectrometer. compared to heavier nuclei, we expect Continuous circularly polarized light The final electrostatic elements of that 8Li will act as a high resolution from a single frequency ring dye laser the beamline are used to focus and steer probe of internal magnetic fields in (300mW power) is directed along the the beam to the sample. This tuning is solids. Although the intrinsic resolution beam axis [10]. The first step in the achieved by placing a plastic scintillator determined by the 8Li lifetime and its procedure is to neutralize the ion beam at the sample position and viewing it gyromagnetic ratio is a few mG, the line by passing it through a Na vapor cell. with a CCD camera. 8Li decays to 8Be, broadening in solids limits this to about The neutral beam then drifts 1.9 m in which in turn promptly decays into two 500 mG. Nevertheless, this is an order the optical pumping region in the energetic alphas of 1–2 MeV. The of magnitude greater than is possible presence of a small (1 mT) longitudinal resulting light emitted from the with muon spin rotation. magnetic field. The D1 atomic transition scintillator is easy to detect with 2 → 2 2s S1/2 2p P1/2 of neutral Li occurs at exposure times of about 1 s. Analysis Polarized 8Li Beam 671 nm. After about 10–20 cycles of of the images (see Figure 3) indicates Large nuclear polarization of the absorption and spontaneous emission, that more than 95% of the beam falls low energy 8Li+ beam is created using a high degree of electronic and nuclear within 4 mm diameter. This defines the
Figure 2. A schematic of the ISAC polarizer. A 30 keV 8Li+ ion beam is neutralized Figure 3. 8Li beamspot image from a in the Na cell and then reionized in the He cell. In the intermediate drift region, a small scintillator in the high field dye laser is used to pump the D1 optical transition of the 8Li atom with circularly spectrometer observed with a CCD polarized light. The resulting polarized ion beam is guided to either the β-NQR camera. More than 95% of the beam is spectrometer or the high field β-NMR spectrometer estimated to fall within a 4 mm diameter.
28 Nuclear Physics News, Vol. 15, No. 1, 2005 facilities and methods
measurements in high magnetic fields, where both the incoming ions and outgoing betas are strongly focused by the magnet. The forward detector is on the beam/magnet axis and is located several cm downstream of the sample. In order to detect betas in the backward direction (opposite to the beam direction), it is necessary that the detector be outside the magnet because the betas are confined to the magnet axis while inside the magnet bore. Although the solid angles subtended by the two detectors in the zero field are Figure 4. A schematic of the high field β-NMR spectrometer. The beam passes very different, they have similar through a small hole in the B detector and then is focussed onto the sample in the detection efficiencies in high magnetic bore of a 9T superconducting solenoid. fields due to this focusing effect. The spectrometer and final leg of the beamline are UHV (ultra high vacuum) minimum area of a sample that can be voltage, magnetic field, and beam compatible in order to avoid a buildup studied. energy. of residual gases on the surface of the The nominal energy of the beam (30 The spectrometer has longitudinal sample. Differential pumping is used to keV) corresponds to an average geometry, such that the polarization and reduce the pressure from 10-7 torr implantation depth of about 200 nm. magnetic field are both along the upstream of the spectrometer to 10-10 torr However, the β-NMR spectrometer sits beam axis. This is necessary for in the main chamber. The sample on a high voltage platform so that the energy of implantation can be adjusted. Recently we have demonstrated that it is possible to decelerate such a beam down to 84 eV. A similar platform is currently being designed for the β-NQR spectrometer. In this way it is possible to measure resonances as a function of implantation depth in the range of 5– 200 nm.
Spectrometers
High Field β-NMR Spectrometer A schematic of the spectrometer is shown in Figure 4. The polarized beam enters from the left and passes through a hole in the back detector before entering the last Einzel lens at the entrance to the high-homogeneity 9 T superconducting solenoid. The beam spot at the center of the magnet is a Figure 5. Photograph of the spectrometer on the high voltage platform. The bellows sensitive function of the Einzel lens has been extended so that the sample and cryostat is in the loading position.
Vol. 15, No. 1, 2005, Nuclear Physics News 29 facilities and methods
the beam and polarization direction.
Example Results
β-NMR in a Ag Film on a MgO Substrate Depth profiling with β-NMR was demonstrated by implanting the beam into a 19 nm–thick Ag film grown on a single crystal of MgO. The sample was provided by T. Hibma from the University of Groningen. Figures 7b and 7c shows the resulting β-NMR spectra for two different implantation energies. In Figure 7c the high voltage platform is grounded so that the 8Li Figure 6. Photograph of the gold foil being loaded into the UHV vacuum chamber stops almost entirely in the MgO of the high field β-NMR spectrometer. substrate. At all temperatures a single narrow line is observed in the MgO. The absence of any quadrupolar cryostat is mounted on a large bellows, field to within 0.005 mT. The oscillating splitting indicates that the electric field gradient at the stopping site is almost so that it can be withdrawn from the H1 field is applied in the vertical magnet bore in order to change the direction which is perpendicular to both zero as expected for the tetrahedral sample through a load lock on top of the main vacuum chamber. The photograph in Figure 5 shows the magnet, bellows, and load lock from the back end. Figure 6 shows a gold foil being loaded into (b) the UHV chamber through the lock. Plastic scintillation detectors are used 8 → 8 ν to detect the betas from Li Be + e – + e , for which the end point energy is (a) 13 MeV.
(c) β-NQR spectrometer The β-NQR spectrometer is less complicated. The beam enters the ultra high vacuum chamber with initial polarization transverse to the beam direction. The β’s pass through thin β stainless steel windows and are detected Figure 7. -NMR spectra on a 20 nm of epitaxially grown Ag film on a MgO in left and right detectors placed substrate. In (c) the implantation energy is 30 keV so that the signal comes from symmetrically on either side of the the MgO substrate. The resonance position in MgO is determined primarily by sample and parallel to the initial the applied magnetic field because it is an insulator and the chemical shifts are polarization direction. A set of three only a few ppm. In (b) the energy of implantation is 1 keV so that a significant magnetic coils are present that allow fraction of the beam stops in the Ag film. The two additional resonances are one to apply a static uniform magnetic attributed to Ag where hyperfine coupling to the conduction electrons produces a field (0–15 mT) along the initial site-dependent Knight shift. The higher frequency line is attributed to the 8 polarization direction, or to zero the octahedral interstitial site whereas, the lower frequency line is due to Li at a subsitutional site.
30 Nuclear Physics News, Vol. 15, No. 1, 2005 facilities and methods
interstitial and substitutional sites. The position of the resonance is determined by the applied field because the local static susceptibility in a non-magnetic insulator is small. The frequency spectrum in Figure 7b is taken with the platform voltage set to 1 keV below the beam energy. In this case most of the beam stops in the Ag film. The residual MgO signal is attributed to part of the beam that lands in an area of the the substrate not covered by the film. Two additional resonances in Figure 7b occur at slightly higher frequencies and Figure 8. The β-NQR spectrum obtained for a SrTiO single crystal at room are attributed to 8Li in the thin Ag film. 3 temperature in zero external field. The resonance occurs when the frequency of Again the absence of quadrupolar H equals 3v corresponding to the m=2 to m=1 quadrupolar transition frequency. splittings imply that both resonances 1 q The inset shows the location of the Li ion at the face center of the cube. originate from sites with cubic symmetry. The resonances are shifted relative to MgO due to the hyperfine ν interaction with the conduction NMR of small metallic particles has The energy eigenvalues Em = h q electrons of Ag. These metallic revealed interesting but poorly (m2 – 2) are a function of the azimuthal
“Knight” shifts are on the order of a few understood confinement effects [18] quantum number m where Iz|m>= hundred ppm as expected for a light ion Such finite size effects may be m|m>. In the zero applied field there are such as Li. A recent study of these lines elucidated by doing β-NMR on thin two resonant frequencies (for I = 2) at ν ν as a function of temperature concludes metal films, wires, or dots. q and 3 q corresponding to the allowed that the higher frequency line comes magnetic dipole transitions 8 β from Li at the octahedral interstitial site -NQR in SrTiO3 0 ↔ ±1 and ±1 ↔ ±2, respectively. The (labeled O in Figure 7a), whereas the In many materials the local site amplitude of each resonance is directly lower frequency resonance is from the symmetry in less than cubic. In this case proportional to the induced change in there is an electric field gradient at the ν substitutional site [22] (labeled S in the nuclear spin polarization Pz( ) on Figure 7a). The lines are remarkably 8Li nucleus that couples to the small resonance. sharp, confirming that the implanted Li electric quadrupole moment of 8Li and Figure 8 shows the β-NQR resides in sites that are well away from produces an energy splitting between spectrum taken on a single crystal of the nuclear spin states in the zero any radiation damage. SrTiO3, which is a common substrate There are several applications of magnetic field. This complicates the β- used in the growth of thin films such as this result. Because Ag is relatively inert NMR spectrum in an applied field and high Tc superconductors. A large and can be easily evaporated onto any can lead to many small resonances. resonance occurs at a frequency β However the simplicity is restored in ν surface, one could use the -NMR corresponding to 3 q. Note that 80% of resonance to measure the magnetic field zero applied field where the spin the polarization is destroyed on distribution near the surface of a Hamiltonian reduces to: resonance. This is about 10 times larger material with a resolution of about 0.5 than the amplitude estimated assuming ν 2 G. In this way the polarized low energy Hq = H q[Iz – 2] (2) the simple spin Hamiltonian above. beam can be used as a kind of local This amplification of the resonance can ν 2 ν magnetometer. For example, one could Here q= e qQ/8, eq = zz is the electric be explained with a slightly non-axial use this method to characterize the field gradient (EFG), Q is the electric electric field gradient at the Li site, vortex lattice near the surface of a quadrupole moment of the nucleus, and which leads to mixing of the m = ±1 superconductor. Also, conventional zˆ is symmetry axis of the EFG tensor. states and causes most of polarization
Vol. 15, No. 1, 2005, Nuclear Physics News 31 facilities and methods
to be destroyed on resonance [23] 3. R. F. Kiefl et al., Physica B 289–290 Kreitzman, C. D. P. Levy, R. Poutissou, β-NQR also has many applications (2000) 640–647. R.H. Heffner, J.E. Elenewski, L. H. because it can be done in a zero static 4. H. Ackermann, P. Heitjans and H.-J. Greene, Phys. Rev. Lett., 93 (2004) Stöckmann in Hyperfine Interactions of 157601. applied field. For example one can use Radioactive Nuclei J. Christiansen, ed., 23. Z. Salman, E. P. Reynard, W. A. it to characterize the superconductivity Topics in Current Physics Vol. 31 MacFarlane, J. Chakhalian, K. H. Chow, near the surface or interface of a high (Springer, Berlin, 1983), p. 291. S. Kreitzman, S. Daviel. C. D. P. Levy, Tc superconductor. Under certain 5. P. Heitjans, W. Faber, A. Schirmer, R. Poutissou, and R. F. Kiefl, Phys. Rev., circumstances we expect the J. Non-Cryst. Solids 131 (1991) 1053– B 70 (2003) 104404. superconductivity to be different near 1062. the surface than in the bulk. Some 6. B. Ittermann, G. Welker, F. Kroll, F. R.F. KIEFL theories predict a broken time reversal Mai, K. Marbach, and D. Peters, Phys. TRIUMF, Vancouver, BC, Canada Rev. B 59 (1999) 2700. and Department of Physics symmetry leading to small magnetic 7. T. R. Beals et al., Physica B 326 (2003) β and Astronomy fields that would be evident in the - 205. University of British Columbia, NQR spectrum 8. E. Morezoni, et al Physica B 326 (2003) 196. Vancouver, BC, Canada and Canadian Institute for Summary and Conclusion 9. R.F. Kiefl et al., Physica B 326 (2003) Advanced Research, We have demonstrated that it is 189–195. 10. M. Keim, U. Georg, A. Klein, R. Canada possible to carry out β-detected NMR Neugart, M. Neuroth, S. Wilbert, P. and β-detected NQR using a beam of Lievens, L. Vermeeren, and the K. H. CHOW 8 + low energy, highly polarized Li . ISOLDE Collaboration, Hyperfine Department of Physics Depth profiling of the signals can be Interactions 97–98 (1996) 543. University of Alberta done on a nanometer scale. We 11. C. D. P. Levy et al., NIM B 204 (2003) Edmonton, AB, Canada anticipate that the technique will have 689–693. 12. M. H. Cohen and F. Reif, Quadrupole many applications in studies of ultra- W. A. MACFARLANE thin films, interfaces, and other issues Effects in Nuclear Magnetic Resonance Studies of Solids, Solid State Physics Department of Chemistry, related to electron confinement where 5, (1957) 321–438. University of British Columbia, it is difficult to obtain equivalent 13. T. P. Das and E. L. Hahn, Nuclear Vancouver, BC, Canada information using conventional NMR. Quadrupole Resonance Spectroscopy, Academic Press Inc. (1958). G. D. MORRIS Acknowledgments 14. C. H. Townes and A. L. Schawlow, C. D. P. LEVY This work was supported by the Microwave Spectroscopy, McGraw-Hill Z. SALMAN CIAR, NSERC, and TRIUMF. We also Book Company (1955). TRIUMF 15. W. A MacFarlane et al., Physica B 326 Vancouver, BC, Canada wish to acknowledge many people at (2003) 209. TRIUMF who have helped make these 16. W. Körner et al., Phys. Rev. Lett., 49 experiments possible, especially (1982) 1735. Donald Arseneau, Rick Baartman, 17. Y. Inaguma et al., J. Electrochem. Soc., Suzannah Daviel, Syd Kreitzman, and 142 (1995) L8; and Solid State Ionics Rene Poutissou. We also thank Rahim 79 (1995), 91. Abasalti and Bassam Hitti for superb 18. H. Brom and J. J. van der Klink, Prog. NMR Spect. 36, 89 (2000) and technical support. Finally, we thank references therein. Laura Greene for providing the SrTiO3 19. Ch. Niedermayer et al., Phys. Rev. Lett., sample and T. Hibma for the Ag film. 83 (1999) 3932 . 20. H. Hoffsass and G. Lindner, Phys. Rep., References 201 (1991) 121. 1. C. P. Slichter, in Principles of Magnetic 21. M. Füllgrabe et al., Phys. Rev., B 64 Resonance, third ed., Springer-Verlag, 224302 (2001) and references therein. New York, 1990., pp. 485–500. 22. G. D. Morris, W. A. MacFarlane, K. H. 2. C. S. Wu et al., Phys. Rev., 105, (1957) Chow, R. F. Kiefl, Z. Salman, D. J. 1413. Arseneau, A. Hatakeyama, S. R.
32 Nuclear Physics News, Vol. 15, No. 1, 2005 meeting reports
Report on the 8th Nuclei in the Cosmos Conference
The 8th Nuclei in the Cosmos conference was held from July 19 to July 23, 2004 at the Coast Plaza Hotel, located in the English Bay area of Vancouver, British Columbia, Canada. Hosted by TRIUMF (Canada’s National Laboratory for Nuclear and Particle Physics) and chaired by L. Buchmann, approximately 273 registered participants (~30% female) were treated to the latest news from the world of nuclear astrophysics and related fields. This series of conferences was established in 1990 with the inaugural meeting being held in Austria. Participants at the Nuclei in the Cosmos 2004 Conference The early emphasis on experimental nuclear astrophysics has now been 60 extended to include a wide range of observation of the Fe (t1/2 = 1.5 Myr) achieved by various groups, more work topics from observational astronomy to in ferromanganese crust in the Pacific. is needed. stellar modeling under extreme This isotope can only have been The LUNA (Laboratory Under- conditions. produced in a SN explosion that ground for Nuclear Astrophysics) The conference was started in a occurred in the solar vicinity at in the facility, located in the Gran Sasso tunnel unique fashion with Tom Lehrer’s past 3 Myr. The Cosmic Ray Isotope in Italy, allows measurements of rendition of “The Elements”; as the Spectrometer (CRIS) on ACE important reactions such as radiative focus of these meetings is the origin of spacecraft, measuring the isotopic proton capture on 14N at very low the elements in the universe. Opening composition of cosmic rays, observes energies. With the reduction of cosmic talks on core collapse supernovae (SN) a source similar to the elements in the ray background, studies down to the of massive stars reported significant solar system. Since 2002 the European Gamow energy window can be advances in understanding these Space Agency’s INTEGRAL satellite achieved. mechanisms that have led to a working has been observing gamma rays emitted A highlight of the conference was model of such SN explosions although from specific isotopes in our Galaxy, the series of talks on SN and gamma- calculations with the most advanced including annihilation radiation and ray bursts (GRBs), exhibiting energies physics have difficulties simulating an 26Al. Such astronomical observations of ~1052 ergs. Overwhelming evidence explosion. Additional data on electron are putting hard constraints on over the last 6 years indicates that a capture rates for the iron group nuclei mechanisms and pushing for more large fraction of GRBs are are needed. The observation of the precise experimental measurements in accompanied by SN Ic, although the 26 gamma emitting isotope, Al (t1/2 = 7.4 the laboratory. inverse is not necessarily true. Models × 105 yr) resulting from SN (and other The reaction considered the most of such violent explosions (collapse explosive events) has stimulated the important in the understanding of the magnetar) were presented as a work in drive to measure reaction rates for its production of elements in stellar progress; the role of rotation and the production and destruction in such environments is 12C(α,γ)16O. It is the emission of jets are important aspects events. However, it is not understood subject of many experimental studies of such scenarios. Of equal importance why 60Fe has not yet been observed by that attempt to measure its rate at stellar is a good understanding of SN 1a, γ-ray astronomy. temperatures with greater precision. which are excellent cosmological An exciting development was the Although significant progress has been distance indicators (standard candles)
Vol. 15, No. 1, 2005, Nuclear Physics News 33 meeting reports
but more effort is needed on their stable and radioactive heavy ion beams. elements. explosion physics. Areas of focus are measurements for In addition there were talks on Considerable progress has been the r-process, the rp-process and the p- reactions occurring in the sun, made in understanding the s-process but process. The combination of these data measurements of the solar neutrino flux more work is needed especially with coupled with improved stellar models using the Sudbury Neutrino initiation reactions and for reactions of lead to a better understanding of Observatory (SNO), and the status of low cross-section and at very low nucleosynthesis in stellar environments information of reactions in Big Bang energies. A new facility, the n_TOF prior to and during explosive scenarios. nucleosynthesis. system at CERN, is now operational Studies on presolar grains are also At the banquet held at the University and providing valuable (n,γ) cross- providing a wealth of new information of British Columbia’s Museum of sections over a wide mass range and and setting constraints on models of Anthropology, all were treated to an energies. nucleosynthesis and stellar evolution. introspective view of the early days of A number of talks were centered on Mechanism of cataclysmic stellar studies at the first center of the r-process in SN explosions, which events, including novae and X-ray experimental nuclear astrophysics at is believed to be the mechanism bursts, were the subjects of various talks Caltech by D. D. Clayton. His talk was responsible for the production of half at the conference. New techniques in entitled, “Phive Years of Physics Phun of the elements heavier than iron. this area involve radioactive beams and with Phowler,” presenting stories of Identification of the astrophysical site recoil separators (such as DRAGON at working with Willie Fowler (Nobel and the specific conditions under which TRIUMF) are providing new avenues Laureate in 1983). the r-process takes place remains a to obtain necessary information The next conference will be hosted major mystery, along with predictions previously considered inaccessible. by CERN in 2006. of properties of very neutron-rich exotic Additional reaction rates involving nuclei involved in this process. exotic nuclei are still required for a JOHN M. D’AURIA There were a number of overview clearer understanding of the mechanism TRIUMF, Canada talks on experimental studies with both leading to the production of particular
International Conference on Nuclear Data for Science and Technology
The scope of the extensive field of scientists and engineers, there is an in applications; they are tested through nuclear data is remarkably little known extensive international effort on benchmark experiments; and they are in the nuclear physics community improving the knowledge of these used in a very wide range of except for a few products including fundamental data and on making these applications. This Conference included charts of the nuclides, tables of data accessible to all. all of these activities with the goal of isotopes, nuclear wallet cards, nuclear In the artistic and historic city of improving nuclear data, identifying structure files, and nuclear structure Santa Fe, the International Conference areas of data needs where progress is references. How these products are on Nuclear Data for Science and required, and providing reliable data for created is even less well known. For Technology (“ND2004”) was held on applications including fission and applications extending from the design September 26–October 1 2004. This fusion energy, accelerator-driven of basic physics experiments to Conference focused on nuclear data, systems, accelerator technology, research and development of nuclear their production, compilation, spallation neutron sources, nuclear techniques and effects in energy, space, evaluation, dissemination, testing, and medicine, environment, geological medicine, geology, homeland security, application. The data are produced both exploration, space, nonproliferation, and so forth, detailed information on the through experiment and theoretical nuclear safety, astrophysics and structure and interactions of nuclei is models; they are compiled and cosmology, and basic research. essential. Fortunately for nuclear evaluated to form data libraries for use This conference was part of a series,
34 Nuclear Physics News, Vol. 15, No. 1, 2005 meeting reports
held in recent years under the auspices much wider use of computer international collaboration, and many of the OECD Nuclear Energy Agency, simulations, and increased confidence papers were presented describing with preceding meetings in Harwell in these simulations from well- various advances in this database. (1978), Gaithersburg (1979), Antwerp characterized benchmark experiments. Nuclear cross-sections are provided in (1982), Santa Fe (1985), Mito (1988), An indication of the scope of the a number of databases in different Juelich (1991), Gatlinburg (1994), conference is given by the four plenary regions of the world. The U.S. cross- Trieste (1997), and Tsukuba (2001). talks: Phillip Finck (Argonne) section data are given in the ENDF file, The present meeting was attended by “Developments in Nuclear Energy and those from Europe, Russia, Japan, 445 participants from 31 countries Technologies and Nuclear Data and China are the JEFF, BROND, including the USA (187), Japan (52), Needs”; Dirk Dubbers (Heidelberg and JENDL, and CENDL files, respectively. Russia (34), France (28), Germany Grenoble) “Particle Physics with Cold Many talks addressed cross-section (25), and Belgium (14). The meeting Neutrons”; Rick Norman (Berkeley and improvements in these files. A new received support from the Los Alamos Livermore) “An Eclectic Journey release of ENDF, the ENDF/B-VII, is National Laboratory; the U.S. through Experimental Physics, or How scheduled for 2005, and much attention Department of Energy’s National I Learned to Stop Worrying and Love was paid to presenting advances in this Nuclear Security Adminstration, Office Nuclear Data”; and James Ziegler (U.S. database and the integral data testing of Science, and Office of Nuclear Naval Academy) “The Importance of used to validate these data. These cross- Energy, Science and Technology; the Nuclear Data to Modern Technology.” section databases are used by radiation International Atomic Energy Agency Prof. D. Allan Bromley gave the transport codes for design and and exhibitors. The program consisted banquet speech on “Advising the simulation in nearly all nuclear of 1 banquet speech, 4 plenary talks, President.” Memorial sessions were technologies. 71 invited talks, 84 contributed oral held as tributes to the extensive The program and abstracts of talks, 1 invited panel, and 326 posters. contributions of S. Raman (Oak Ridge) ND2004 can be found at the Con- Highlights of the meeting included and S. Pearlstein (Brookhaven) to this ference website: http://t16web.lanl.gov/ new experimental facilities and field. nd2004/. Proceedings will be published techniques, significant improvements Nuclear data are available to users by the American Institute of Physics. in nuclear reaction models, deve- around the world through a number of The next conference in this series, lopments in fundamental physics, nuclear databases that contain the most ND2007, is anticipated to be held in continuing improvements and tests of precise information available on nuclear France in May 2007. nuclear data libraries, enhanced structure properties and nuclear reaction ROBERT C. HAIGHT dissemination of nuclear data, increased cross-sections. The ENSDF (Evaluated AND MARK B. CHADWICK emphasis on integral experiments as Nuclear Structure Data File) is Co-chairs, ND2004, constraints on the microscopic data, maintained and improved via an Los Alamos National Laboratory
Vol. 15, No. 1, 2005, Nuclear Physics News 35 news and views
NSAC Activities—2003/2004
The Nuclear Science Advisory Table 1. NSAC Activities—2003/2004 Committee (NSAC) plays a role in the Charges (short titles) Chairs U.S. somewhat analogous to that of NuPECC in Europe although these two Facilities Charlie Glashausser, Rutgers committees function differently. NSAC Fundamental NP with Neutrons Bob Tribble, TAMU directly advises the two nuclear physics Nuclear Theory Berndt Mueller, Duke funding Agencies, the U.S. Department Education Joe Cerny, U.C. Berkeley and LBNL Performance Measures/ Milestones Don Geesaman, ANL of Energy (DOE) and the National Committee of Visitors John Cameron, Indiana Science Foundation (NSF). NSAC is RIA/GSI Peter Bond, BNL typically comprised of about 17 RHI Peter Barnes, LANL members, representing universities and national labs, experimentalists and theorists, and reflecting the diversity in The advice given by NSAC through differed in character from these. One the field. NSAC receives tasks or the work of its sub-committees of these dealt with the development of questions (“charges”) from these contributes valuable guidance and is a set of Milestones and phased Agencies to study various specified often reflected in subsequent funding Performance Measures for each sub- issues and to give guidance. Often, decisions, new initiatives, and altered field over the next decade, for use by these charges are requests to look into priorities. Although the output of the funding Agencies in their certain sub-fields, to identify the most NSAC’s work is advisory only, and assessment of progress in the field. promising scientific opportunities, the funding constraints may limit the Another, the so-called Committee of facility and detector requirements to realization of its recommendations, the Visitors, turned the peer review tables realize them, and to make recom- Agencies seldom act contrary to those on DOE to some extent, providing an mendations to optimize current and recommendations and thus NSAC evaluation of the operations and future investments in the field. plays a significant role in developing processes of the Nuclear Physics Office Frequently, these charges are framed in U.S. funding priorities for nuclear of the Office of Science at the DOE. the context of particular funding science. Finally, a third change dealt broadly scenarios. The years 2003/2004 have been with education and public outreach in Given a charge, NSAC forms a sub- among the most active ever for NSAC. nuclear science, with recommendations committee that studies the issue at hand, There have been a total of 8 charges, as spanning the gamut from the earliest and writes a Report that is submitted to listed in Table 1 by short titles and the school years through the post-doc NSAC. NSAC meets to evaluate the sub-committee chairs. The first on the period, and beyond, looking at national Report and, usually, to transmit it to the list, the Facilities Report, played a needs in pure and applied nuclear Agencies with its concurrence and with significant role in the development of science, the production of new nuclear an accompanying letter expressing the well known 20 Year Facilities Plan scientists, mentoring them on the NSAC’s perspective as well. Once for the DOE, with its very high ranking variety of post Ph.D. careers, and efforts transmitted, these Reports are publicly for RIA. Other charges dealt with to educate the public at large on issues available on the Agencies’ websites. fundamental physics with neutrons, relating to nuclear science. Every six years or so, NSAC also nuclear theory, the relation of RIA and organizes a decadal Long Range GSI in the exotic beam field, and RICHARD F. CASTEN Planning process for the field as a opportunities for new advances in Chair, NSAC whole. relativistic heavy ions. A few charges
36 Nuclear Physics News, Vol. 15, No. 1, 2005 news and views
Oldest Institute of the Austrian Academy of Sciences Renamed as Stefan Meyer Institut für subatomare Physik
On 25 June 2004, the Austrian Academy of Sciences decided to rename its Institute for Medium Energy Physics as Stefan Meyer Institut für subatomare Physik. The former had been the successor institute of the famous “Institut für Radiumforschung,” Logo of the Stefan Meyer Institut Logo of the Austrian Academy which was founded in 1910 as the für subatomare Physik of Sciences world-wide first institute of its kind. Stefan Meyer was the first director. Based on a generous donation of interaction at low energy. It is involved recently been concluded. Preparations Karl Kupelwieser, the “Institut für in several international collaborations. for SIDDHARTA, the successor Radiumforschung” was at that time the Presently, the Stefan Meyer Institut experiment to DEAR are well under first research institute of the then takes part at experiments at the LNF, way. Its goal is the measurement of the “Imperial Academy of Sciences.” Laboratori Nazionali di Frascati in Italy ground state shift and width due to The renaming is connected to a new and at the PSI, Paul Scherrer Institute strong interaction in kaonic deuterium. scientific direction, which was initiated in Switzerland. At the LNF it is member At PSI, the institute is part of the by the last director of the Institute for of the DEAR collaboration, which is Pionic Hydrogen Collaboration, which Medium Energy Physics and first devoted to the study of kaonic aims at the measurement of the director of the Stefan Meyer Institut, hydrogen. An experiment, determining hadronic shift and width of pionic Paul Kienle. the strong interaction shift and hydrogen at the percent level. The Stefan Meyer Institut is doing width of the 2p-1s transition has In November 2004 Eberhard research in the field of strong Widmann was appointed director of the Stefan Meyer Institut. He is head of the spectroscopy group of the ASACUSA collaboration at CERN and con- sequently the institute is part of this collaboration. In the future, the Stefan Meyer Institut will be engaged at FAIR (Facility for Antiproton and Ion Research), the future project of the GSI, Darmstadt. This new line of research takes into account the changing landscape of European nuclear and particle physics. The FAIR project will result in one of the biggest and most complex accelerator facilities in the world. The Stefan Meyer Institut plans to be part of several experiments at FAIR:
Toshimitsu Yamazaki, Pierre Radvanyi, Hélène Langevin-Joliot, Paul Kienle. • At FLAIR (Facility for Low-energy
Vol. 15, No. 1, 2005, Nuclear Physics News 37 news and views
Antiproton and Ion Research), Meyer, being secretary of the Festivity on the Occasion of the where a low energy antiproton beam International Radium-Standard- Renaming of the Stefan Meyer at high intensity is used for Commission, played a crucial role in Institut spectroscopy of antiprotonic atoms the establishment of the so called On the occasion of the renaming of among other fields of research. “Radium standards.” His contribution the Stefan Meyer Institut für subatomare Eberhard Widmann is spokesperson to this ever growing field of physics was Physik, festivities were held on 29 of the FLAIR project. widely recognized and appreciated and October 2004. The names of Stefan • At AIC (Antiproton-Ion-Collider), cumulated in his election as president Meyer, together with Viktor Hess, proposed by Paul Kienle to measure of the International Radium-Standard- Georg V. Hevesy, as well as Marietta the difference of neutron and proton Commission. Forced to retire after the Blau and Berta Karlik, were engraved density distributions of nuclei far off “Anschluss” of Austria to national- in the institutes marble table of honors. stability by medium energy socialist Germany, Stefan Meyer At the premises of the Austrian antiproton absorption. survived the horrors of the Second Academy of Sciences a symposium was • At PANDA (Antiproton Annihi- World War in Bad Ischl. Unlike many held to commemorate the institute’s new lation at Darmstadt) high energy others, he could return to Vienna to see name. Among the many distinguished antiprotons are extracted to the reconstruction of his institute. speakers, Hélène Langevin-Joliot, investigate charmonium, glue-balls, Stefan Meyer died in 1948. granddaughter of Marie Curie, and hypernuclei, and other topics. It was Stefan Meyer, who made Lise Pierre Radvany gave a touching Meitner interested in the physics of personal account of their memories on Stefan Meyer—Austrian Pioneer radioactivity. During his directorship the early days of radioactivity research of Nuclear and Particle Physics Viktor Hess and Georg V. Hevesy and the most prominent persons. Born in Vienna in 1872, Stefan worked at the institute, who become Paul Kienle summarized the spirit Meyer was one of the pioneers of Nobel laureates in 1936 and 1948, of the day: “The Stefan Meyer Institute modern nuclear and particle physics in respectively. Viktor Hess, being Stefan I wish all the best for the future and Austria. He organized the construction Meyer’s research assistant, discovered success in its scientific projects. Meet of the “Institut für Radiumforschung” cosmic rays during his balloon flights. the challenge of your demanding name! in Vienna and headed this research Georg V. Hevesy, hearing about the Standing in a tradition, create a new institute as its first director from 1910 excellent experimentalists at the one!” to 1938. In the early days of research Radiuminstitut, came to Vienna to on radioactivity the then Austro- perform his first experiments on the HERMANN FUHRMANN Hungarian monarchy was the only radioactive tracer method. Stefan Meyer Institut supplier of radium samples, due to its By naming this institute after Stefan für Subatomare Physik Austrian mines in Joachimsthal, now part of the Meyer, the Austrian Academy of Academy of Sciences Czech republic. Together with Marie Sciences is honoring one of its most More information and photos are found at: http://www.oeaw.ac.at/smi Curie and Ernest Rutherford, Stefan excellent scientists.
38 Nuclear Physics News, Vol. 15, No. 1, 2005 calendar
2005 September 4–9 March 13–20 May 27–31 Notre Dame, Indiana, USA. 12th Bormio, Italy. XLIII International Aschaffenburg, Bavaria, Germany. International Conference on Capture Winter Meetings on Nuclear Physics. SHIM 2005: Swift Heavy Ions in Gamma-Ray Spectroscopy & Contact: Prof. I. Iori, Bormio Winter Matter. Contact: Stefanie Lüttges, Related Topics. Contact: Prof. Ani Meeting, Dipartimento di Fisica, Via Gesellschaft für Schwerionenforschung, Aprahamian, 225 Nieuwland Science Celoria 16, 20133 Milano, Italy. Planckstr. 1, D-64291 Darmstadt, Tel.: Hall, University of Notre Dame, IN [email protected] +49 6159-71-2721; Fax: +49 6159-71- 46556-5670, USA. Fax: 574-631-5952. 2134, [email protected] E-mail: [email protected] March 19–23 Web: http://www.gsi.de/SHIM2005 Web: http://www.nd.edu/~nsl/cgs12/ San Servolo, Italy. FUSION06, International Conference on Reaction June 14–18 September 5–9 Mechanisms and Nuclear Structure at Lund, Sweden. International Pavia, Italy. The XIX Nuclear the Columb Barrier. Contact: Lorenzo Conference on Finite Fermionic Physics Divisional Conference Corradi, Chair. [email protected] Systems, Nilsson Model 50 Years. (NPDC19) of the European Physical Web: http://www.lnl.infn.it/~fusion06/ Web: http://www.matfys.lth.se/ Society. Nilsson Web: http://www.pv.infn.it/~npdc19 March 29–April 5 Kloster Banz, Germany. Neutron- June 20–25 September 10–14 Rich Radioactive Ion Beams— Debrecen, Hungary. Exotic Zaragoza, Spain. Ninth Interna- Physics with MAFF. Contact: R. Nuclear Systems (ENS ‘05). tional Conference on Topics in Fischer, Dept. of Physik, Universität Web: http://www.atomki.hu/ens05/ Astroparticle and Underground München, Am Coulombwall 1, 85748 Physics (TAUP). Contact: TAUP 2005 Garching, Germany. Tel.: +49 89 289 June 28–July 1 Secretariat, Ms. Mercedes Fatás, 14078. E-mail: [email protected] St. Petersburg, Russia. LV [email protected] muenchen.de International Meeting on Nuclear Web: http://www.unizar.es/taup2005 Web: http://www.ha.physik.uni- Spectroscopy and Nuclear Structure. muenchen.de/maff/workshop Contact: Dr. A. Vlasnikov, Institute of September 12–17 Physics, St. Petersburg State University, Kos, Greece. Frontiers in Nuclear May 16–20 Uljanovskaja Str., 1, Petrodvorets, St. Structure, Astrophysics, and Debrecen, Hungary. Nuclear Petersburg, Russia, 198504. E-mail: Reactions Conference (FINUSTAR). Physics in Astrophysics - II. [email protected] Contact: [email protected]. Web: http://atomki.hu/~npa2/ Web: nuclpcl.phys.spbu.ru/nuclconf Web: http://www.inp.demokritos.gr /~finustar May 16–22 August 25–September 2 Bonn, Germany. International Mainz, Germany. Euro Summer September 12–15 Conference on Low Energy School on Exotic Beams. Contact: E- Caen, France. 11th International Antiproton Physics (LEAP-05). mail: [email protected] Conference on Ion Sources ICIS05. Contact: Walter Oelert, Institut für Web: http://www.ganil.fr/icis05 Kernphysik, Forschungszentrum Jülich August 30–September 6 GmbH, D-52425 Jülich, Germany. Tel.: Piaski, Poland. XXIX Mazurian September 19–24 +49 2461 61 4156. Fax: +49 2461 61 Lakes Conference on Physics: Milos, Greece. 6th Research 3930. E-mail: [email protected]. “Nuclear Physics and the Funda- Conference on Electromagnetic Web: http://www.gsi-bonn.de mental Processes. Interactions with Nucleons and Web: http://zfjavs.fuw.edu.pl/ Nuclei (EINN 2005). Contact: Paul May 23–26 mazurian/mazurian.html Hoyer. Email: [email protected] Bonn, Germany. 6th International Web: http://www.iasa.gr/EINN_ Conference on Nuclear Physics at 2005/EINN05/ Storage Rings STORI05. Web: http://www.fz-juelich.de/ikp/ stori05/
Vol. 15, No. 1, 2005, Nuclear Physics News 39 calendar
October 3–7 November 23–25 September 2–6 Iguazú, Argentina. The Sixth Brussels, Belgium. 3rd Rio de Janeiro, Brasil. Latin American Symposium on International Conference on International Conference on Nucleus- Nuclear Physics and Applications. Education and Training in Nucleus Collisions NN2006. Contact: Contact: [email protected]. Radiological Protection (ETRAP). [email protected] Web: http://www.tandar.cnea.gov. Contact: Dionne Bosma, Conference ar/misc/SLAFNAP6.php Coordinator, etrap2005@euronuclear. org October 16–22 Web: http://www.etrap.net/ More information in Dresden, Germany. Workshop on Critical Stability. Contact: Aksel S. 2006 the “Calendar” on Jensen, [email protected] or Laurent March 19–23 http://www.nupecc.org Wiesenfeld, laurent.wiesenfeld@ujf. San Servolo, Italy. FUSION06, grenoble.fr. International Conference on Reaction Web: http://www.mpipks-dresden. Mechanisms and Nuclear Structure at mpg.de the Columb Barrier. Web: http://www.lnl.infn.it/ ~fusion06/
40 Nuclear Physics News, Vol. 15, No. 1, 2005