PoS(Confinement2018)215 , a , i , ad , L. De , c i , M. Iliescu a , https://pos.sissa.it/ a f , C. Berucci NE Collider c , S. Nied´zwiecki i , M. Silarski Φ d , a A. Dawood Butt a , C. Guaraldo g , G. Bellotti , H. Shi , P. Moskal a a a , O. Vazquez Doce k , F. Ghio c , C. Curceanu , M. Bazzi d c , A. Scordo , M. Miliucci a j ad , H. Tatsuno , C. Fiorini a f , M. Cargnelli b , J. Marton , A. Baniahmad a c ad , K. Piscicchia ab , A. Spallone i , L. Fabbietti a , J. Zmeskal d , P. Levi Sandri , A. Amirkhani , M. Bragadireanu h , M. Skurzok e , D. Pietreanu b ab h , ∗ a R. Del Grande a Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). E. Widmann F. Sirghi Paolis M. Iwasaki S. Okada D. Sirghi Kaonic atoms measurements at the DA D. Bosnar PoS(Confinement2018)215 and , , , , , , , , ˙ I, Roma, Italy . ˘ , , A , , , , , ˘ AIJEnrico Fermiâ [email protected] [email protected] , , [email protected] , [email protected] [email protected] , , [email protected] , [email protected] [email protected] , , [email protected] , [email protected] [email protected] [email protected] [email protected] , , , , [email protected] [email protected] , , , [email protected] , [email protected] , [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Excellence Cluster Universe, Technische Universiät München, Garching, Germany INFN Sez. di Roma I and Inst. Superiore di Sanita, Roma, Italy RIKEN, Tokyo, Japan The M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland Museo Storico della Fisica e Centro Studi e Ricerche â Stefan-Meyer-Institut für Subatomare Physik, Vienna, Austria Department of Physics, Faculty of Science, University of Zagreb, Croatia Lund Univeristy, Lund, Sweden E-mail: Horia Hulubei National Institute of PhysicsRomania and Nuclear Engineering (IFIN-HH), Magurele, Politecnico di Milano, Dipartimento di Elettronica,Sezione Informazione di e Milano, Bioingegneria Milano, and Italy INFN INFN, Laboratori Nazionali di Frascati, Frascati (Roma), Italy i j f e c k g h d b a PoS(Confinement2018)215 d results. An overview of the experi- − -series; the accurate measurement of the K p and the upcoming K − level shift and width induced by the presence of the strong interaction; an 1s NE electron-positron collider of the Laboratori Nazionali di Frascati of INFN is a world- Φ level shift and width of kaonic helium-4 and kaonic helium-3; yields of various light kaonic Speaker. upper limit of the X-ray yield for kaonic deuterium The DA wide unique low-energy kaon source, which is beingthe used SIDDHARTA to collaboration. produce The and to X-ray study measurements kaonic of atoms kaonicfor by atoms understanding play the an low-energy important role QCD inbeen the obtained strangeness by the sector. SIDDHARTA experiment, Significant among achievementsmeasurement which: have of the the most precise kaonic hydrogen 2p atoms transitions. Using the experiencedeuterium gained measurement with is SIDDHARTA in experiment, preparation thewith in first the the kaonic goal framework to of determinepossible the the only SIDDHARTA-2 antikaon-nucleon by experiment, isospin combining the dependent K scatteringmental results lengths, of which SIDDHARTA is and anpaper. outlook to SIDDHARTA-2 experiments are given in this ∗ XIII Quark Confinement and the Hadron31 Spectrum July - - Confinement2018 6 August 2018 Maynooth University, Ireland PoS(Confinement2018)215 D. Sirghi ) and the width ε state due to strong interaction are p 1 NE ground state, which is shifted due to strong interaction and broadened due to nuclear Φ s ]. Cascade processes for kaonic hydrogen, starting when the kaon is captured in a highly excited 1 25 excited state for kaonic hydrogen (as an example) by replacing an electron. Slowing ' Since the atomic binding energies of light kaonic atoms are in the keV range, the kaonic atoms For the study of the strong interaction the observables of interest are the shift ( A kaonic atom is formed when a negative kaon enters a target and is slowed down to a kinetic ) of the atomic level, caused by the strong interaction, relative to the electromagnetic value. Γ ( The electromagnetic values of thethe energy Klein-Gordon levels can equation. be Even calculatedinformation a at of small a the deviation precision strong from of interaction the eV between the by electromagnetic kaon solving value and allows the to nucleus. get offer the unique opportunity toenergy. perform This experiments allows equivalent to the scattering studythe at of need vanishing the of relative antikaon-nucleon/nucleus interaction extrapolation “atments to threshold", are zero without the relative studies energy. oflow-energy physics Of systems parameters particular formed like the with interest antikaon-nucleon hydrogen inables scattering isotopes, lengths. kaonic access Kaonic which atoms to deuterium give experi- en- the accessto antikaon-neutron to construct system. the the basic antikaon-nucleus Other interactionlight light from exotic atoms the elements are elementary formed provide reactions. almost information “electron-free",measurements, which It on due opens is to the how noteworthy possibility the for that absence high-precision of electron screening effect. Figure 1: state, down to the 1 absorption of the kaon by the proton. The shift and width of the 2 negligible [ energy of a few tens of eV bykaon ionisations is and excitations stopped of the inside molecules ofthe the the n target. target The and entering isdown captured and by capture a occur on target aexperiences atom time a into series scale of an from deexcitation picoseconds outer processes toemission. atomic which, nanoseconds. at orbit, lower Then, Finally, lying in the the states, kaonic kaon are atom electromagnetic dominated reaches one. by the X-ray ground state where the strong interaction adds up to the Kaonic atoms at DA 1. Introduction PoS(Confinement2018)215 0 < a (1.5) (1.2) (1.6) (1.1) (1.3) (1.4) p/p ∆ D. Sirghi scattering from complex scatter- − p K − NE is a unique low- K ] ] Φ ...... + + ], where the of the isospin- p d 3 scattering lengths one has to − − , and the K K 2 1 s . a a 1 a ] ) ) isospin dependent (I=0,1) scatter- 1 Γ : 1 1 a d 3 − − − KN C and K + α α a s 0 + 1 ] ln ln a , includes all higher-order contributions, ε 1 [ ( ( Q C a ] ] 4 1 NE collider. K K 1 + αµ αµ Φ m m a 2 2 0 and isovector ] = a three-body interaction. n + + [ 0 = − − − 2 1 2 a NE d N N n 1 1 K [ [ − − a m m Φ p d [ = K 2 − − is related to the K [ 4 a + p K K p − p a a scattering length − = K 2 − 2 K a K d d µ µ a -mesons produced almost at rest, which decay with a prob- ]: a − 3 3 − [ 5 K φ α α K 1 2 , a 2 2 4 , can be studied by solving Faddeev-type equations, taking into Factory for Nice Experiments) is a world-class electron-positron = = = Φ s s Q 1 1 Γ Γ KNN i i 2 2 , with a momentum of 127 MeV/c, and a momentum spread − ) represents the lowest-order impulse approximation ( + + s s K 1 1 1.5 + ε ε through the average: K NE 1 a Φ is given by the so-called Deser-Trueman formula [ -wave scattering length p and − ] at the National Laboratories of Frascati (LNF) in Italy. DA 0 p s K 7 a − a , NE (Double Annular 6 K Φ : 1 The SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Applica- The three-body system, DA In the case of kaonic hydrogen the relation between The The first term in ( A similar formula holds for the In order to obtain the individual isoscalar a tion) experiment ended its data taking campaignatoms in transitions November measurements 2009, on after the having upgraded performed DA kaonic ing length where energy kaon source via theability decay of of 48.9% in 0.1%. This “kaon beam”interactions, is a intensively field used still largely for unexplored. studies of the low-energy kaon - nucleon/nuclei account the dynamics of the system, namely specifying the two-body interactions. 2. The SIDDHARTA experiment at DA breaking corrections are included [ ing lengths each (free) nucleon ofnamely deuterium). all other The physics second associated with term, the collider [ Kaonic atoms at DA measure also the kaonic deuterium,and which provides information on a different combination of PoS(Confinement2018)215 ], 10 ]. 12 D. Sirghi NE. A detailed ]. 8 Φ ], [ 11 ]. 8 ]. 9 level, which represents the most precise mea- level - as an exploratory measurement [ s s 3 level, the first measurement ever [ level, the first measurement using a gaseous target [ p p Schematic view of the SIDDHARTA setup [ cells on one silicon wafer, for SIDDHARTA at DA 2 , where a global simultaneous fit of the hydrogen and deuterium spectra 1 cm 3 ]. Figure 2: 9 × NE Φ shows a schematic view of the SIDDHARTA setup, which consisted of three main 2 ]. 11 [ surement ever [ The kaonic hydrogen spectrum together with the deuterium data used for background evalu- The cryogenic gas-target system is a critical element of the experiment, because the yields of The kaonic atoms X-rays were detected using the Silicon Drift Detectors (SDDs). For the During the SIDDHARTA data taking campaign the following measurements were performed: In the SIDDHARTA experiment the monochromatic low-energy charged kaons are degraded Fig. - kaonic helium3 transitions to the 2 - kaonic helium4 transitions to the 2 - kaonic hydrogen X-ray transitions to the 1 - kaonic deuterium X-ray transitions to the 1 ation is shown in Fig. kaonic-atom X-rays decrease sensitively towards higher densitywith due other to atoms. collisions and Stark Forcylindrical mixing this target cell, reason 13.7 it cm ischamber in is and diameter it essential and was to 15.5 filled employ with cm Hydrogen in a at height, low 22 was density K located and gaseous insidefirst p target. =2.5 the time, bar. vacuum large The area SDDs,6 characterized keV) by and good values time of resolutionswere energy (800 developed resolution ns), as (160 which 3 eV turned FWHM out at essential for the background suppression, description of the experimental setup is given in Ref.[ and stopped in a cryogenic gaseous target where kaonic atoms are efficiently produced. Kaonic atoms at DA components: the kaon detector, a X-ray detection system and a cryogenic target system. PoS(Confinement2018)215 α K , cal- α K D. Sirghi -energy level s ) of the 1 s 1 ε ]. This appears to be consistent with 9 shift (negative 4 -series X-rays of kaonic hydrogen were clearly ob- K indicates the X-ray energy of kaonic-hydrogen repulsive-type 3 -series transitions. (b)(c) Measured energy spectra with the fit K X-ray transitions of kaons stopped in the target cell wall made n ) and its support frames made of aluminum. There are also characteristic 2 (a) shows the residuals of the measured kaonic hydrogen X-ray spectrum 3 N 5 NE O Φ 10 H 22 The global simultaneous fit of the X-ray energy spectra of hydrogen and deuterium data. (a) (b) and (c) show the fit result with the fluorescence lines from the setup materials and a 3 ]. 9 The vertical dot-dashed line in Fig. Fig. Many other lines were detected in both spectra, as indicated with arrows in the figure. These Figure 3: Residuals of the measuredclearly displaying kaonic-hydrogen the X-ray kaonic-hydrogen spectrumlines. [ after subtraction of the fitted background, of Kapton (C X-rays from the titanium and copper foils installed for calibration. kaonic atom lines result from high- the theoretical expectation of lower X-ray yield and greater transition width for deuterium . culated using the electromagnetic interactionpeak only. Comparing with the the measured electromagnetic kaonicturned value, hydrogen out. a continuous background. after subtraction of the fitted background. Kaonic atoms at DA was performed. Fig. served, while those for kaonic deuterium were not visible [ PoS(Confinement2018)215 p ]: 2 9 (2.5) (2.4) (2.1) (2.2) → 0.0143, d D. Sirghi < C), kaonic ) − He 3 3 tot K − K ( K 5) is indicated as Al) was also seen. Y − > K n interaction. . The larger absorption α KN K He and the . , -series X-rays of kaonic hy- 4 K − eV eV K ) ) . eV eV a. yield was extracted: syst syst 4 ) ( ( ) α 4 4 K ± ± syst 0012 (2.3) syst ( . ) ) ( 6 0 ]: 22 ± ± stat stat of kaonic hydrogen were determined to be [ 11 ) ( ( ± , s 3 2 ) 1 8 5 , Γ ± ± stat 0019 . ( 5 2 stat 10 0 ( 36 − ]. The use of gaseous targets avoided the weakening of 89 interaction, it is essential to measure the kaonic-deuterium ± ) = = + = are [ ) peaks are seen. Other Balmer series X-rays can be also ± 11 O) were identified as produced from the Kapton polyimide α p p p p , − K 2 2 2 2 KN 283 8 ( and width ε ε Γ K , 541 s − Y 1 → ε 10 = = d and He : He : s s 4 3 1 1 (3 p ε Γ 2 − − α ε K K NE electron-positron collider, both the Φ ) in the case of kaonic deuterium atoms, as compared to kaonic hydrogen, p 2 -level shift Γ s yield. The Kd spectrum is shown in Fig. ]. NE α Φ 12 K N), and kaonic oxygen ( shows the X-ray energy spectra of different target data, (a) deuterium (2.50 g/l), (b) − K 0.0039 [ 4 state (larger p < ) . Such values are compatible with what is expected, namely a yield of a factor about 10 smaller This is the most precise measurement performed so far ofThe precise the determination of the shift and width provides new constraintsFor on a deeper theories, understanding having of the Apart of the kaonic hydrogen and kaonic deuterium measurement, the SIDDHARTA experi- Fig. From the data analysis, the upper limits for the yields turned out (CL 90%): As a result, the 1 The obtained values for Two data sets of helium-4 targets were merged. The systematic uncertainty was calculated as α K ( high than the kaonic hydrogen yield, estimated to be between 1% to 2% for in the 2 causes the lower helium-3 (0.96 g/l), (c) helium-4ray (1.65 peaks g/l), are and indicated (d) for helium-4 the (2.15 deuterium g/l). target data. Several The kaonic X-rays atoms of X- kaonic carbon ( used for the target cell and the target entrance window. The kaonic aluminum ( reached a quality which demands refined calculations of the low-energy ment measured at the DA drogen atoms. transitions using gaseous targets [ the yields due to the Starktainty effect of and, the also, Compton the scattering necessity ofsystematic to X-rays errors take inside in the into the liquid account previous helium the kaonic target, systematic helium-4 which uncer- experiments. was big source of nitrogen ( K-series X-rays to disentangle theexperiment, isoscalar after and performing isovector the scatteringexploratory most study lengths. precise of kaonic measurement The deuterium, on SIDDHARTA from kaonic which the hydrogen, Kd made the first Kaonic atoms at DA It comes from the targetand cell helium-4 frame targets, and clear the L structuresseen of as the smaller SDDs. peaks. For In the the data figure, sets the of sum of helium-3 the higher state transitions ( L the quadratic sum of the individual contributions. Y PoS(Confinement2018)215 (2.6) (2.7) D. Sirghi He SIDDHARTA 4 NE in Sprimg 2019, − Φ K . , eV eV ) ) syst ( syst ( 5 7 ± ± ) ) stat ( stat ( 8 6 6 ± ± 6 14 = = p p 2 2 Γ Γ He : He : 3 4 − − K K NE Φ He measurements were perormed for the first time. The with gaseous target are consistent, within the errors, with the results of the KEK-PS 3 p 2 − X-ray energy spectra of different SIDDHARTA targets data in the synchronous time window, ε K ] with liquid target. 13 The kaonic deuterium X-ray measurement represents the most important experimentalThe infor- experimental challenge of the kaonic deuterium measurement is the very small kaonic SIDDHARTA-2 is a new experiment, which will be installed on DA The taking advantage of the experiencehydrogen and gained kaonic in helium. the preceding SIDDHARTA experiment on kaonic mation missing in the low-energy antikaon-nucleon interactions field. deuterium X-ray yield (one orderthe of magnitude difficulty less to than perform for X-raydelivering hydrogen), kaons. spectroscopy the even in larger the width high and radiation environments of the machines 3. Kaonic deuterium: the SIDDHARTA-2 experiment Figure 4: (a) deuterium (2.50 g/l), (b)positions of helium-3 the (0.96 kaonic g/l), helium X-ray (c) lines helium-4 in (1.65 (b), g/l), (c), (d) and are (d) indicated helium-4 by arrows. (2.15 g/l). The Kaonic atoms at DA results for E570 [ PoS(Confinement2018)215 5 D. Sirghi are those of kaonic hydrogen, with total :K β 7 :K α shows the expected spectrum for an integrated luminosity 6 NE in similar machine background conditiond as in SIDDHARTA . Fig. Φ 3 − NE collider provide unique quality results for the understanding of the low- NE Φ Φ yield of 10 NE collider delivers an excellent quality low-energy charged kaons beam. Such a α delivered by DA Φ 1 The SIDDHARTA-2 setup with the cryogenic target cell surrounded by the SDDs and the Veto-2 − We thank C. Capoccia and G. Corradi, from LNF-INFN; and H. Schneider, L. Stohwasser, and The DA A detailed Monte Carlo simulation was performed within the GEANT4 framework to optimise The goal of the new apparatus is to increase drastically the signal-to-background ratio, by energy QCD in the strangenessto sector, astrophysics. with implications going from particle and nuclear physics 5. Acknowledgments beam was intensively used by thements SIDDHARTA collaboration of to kaonic perform unique atoms. qualitysetup measure- in Presently, order an to enlarged performexperiments collaboration, the on kaonic SIDDHARTA-2, DA deuterium is measurement. upgrading SIDDHARTA the and SIDDHARTA-2 of 800 pb runs. The extracted shift andrespectively, similar width to can the be SIDDHARTA results determined for with kaonic precisions hydrogen. of about 304. eV and Conclusions 80 eV, the critical parameters of the setup, likegeometry. target size, The gas Monte density, detector Carlo configuration simulation and tookassumptions: shielding into account the all values the of improvementseV with shift and the and following 750 width eV, of respectively; the yields 1s ratios ground K state of kaonic deuterium are -800 Figure 5: system within the vacuumoutside. chamber, while the Veto-1 device is surrounding the vacuum chamber on the an assumed K gaining in solid angle, takingadditional advantage veto systems of in new order SDDsshows to with the perform SIDDHARTA-2 improved apparatus. the timing, kaonic and deuterium implementing X-ray measurement. The Fig. Kaonic atoms at DA PoS(Confinement2018)215 D. Sirghi = -800 eV and width s 1 ε (3), 774 (1954). 96 NE staff for the excellent working Φ , 349 (2004). , 473 (2006). 35 47 . The spectrum was simulated for an integrated 3 − 8 , 512 (2008). 61 360 (2009). yield of 10 24 α 174801 (2010). , 387 (2007). 69, (2013). (3), 199 (2011). , 310 (2009). , 40 (2012). , 113 (2011). 104 653 907 , 57 (1961). 697 704 681 714 26 . 1 NE − Φ Simulated SIDDHARTA-2 kaonic deuterium spectrum, assuming a shift = 750 eV of the 1s state, as well as a K s 1 [7] M. Zobov et al., Phys. Rev.[8] Lett. M. Bazzi et al., Phys. Lett.[9] B M. Bazzi et al., Phys. Lett. B [1] J. Zmeskal, Particle and Nuclear Physics [2] S. Deser, M.L. Goldberger, K. Baumann, and W. Thirring, Phys. Rev. [5] U.G. Meißner, U. Raha, and A.[6] Rusetsky, Eur.C. Phys. Milardi J. et C al., Int. J. Mod. Phys. A [3] T.L. Trueman, Nucl. Phys. [4] U.G. Meißner, U. Raha, and A. Rusetsky, Eur. Phys. J. C luminosity of 800 pb D. Pristauz-Telsnigg from Stefan-Meyer-Institut, forand their building the fundamental SIDDHARTA setup. contribution We in thank as designing well the DA [10] M. Bazzi et al., Phys. Lett.[11] B M. Bazzi et al., Phys. Lett.[12] B M. Bazzi et al., Nucl. Phys.[13] A S. Okada, S. et al., Phys. Lett. B Γ conditions and permanent support. Part(FWF): of [P24756-N20]; this Austrian Federal work Ministry was of supported ScienceVI/2/2009; by and the Research the Grantïn-Aid BMBWK Austrian for 650962/0001 Specially Science Promoted Fund Researchtian (20002003), Science MEXT, Foundation, Japan; under the Croa- project 1680;ternazionale, Minstero degli Direzione Affari Generale Esteri per e la dellaproject; Cooperazione Promozione Polish In- del National Sistema Science Paese Center (MAECI), throughof Strange grant Science No. and Matter Higher UMO-2016/21/D/ST2/01155; Education Ministry of Poland grant no 7150/E-338/M/2018. References Figure 6: Kaonic atoms at DA