The Antiproton-Ion Collider

1. The Antiproton-Ion Collider R. Krücken Technische Universität München for the Antiproton Ion Collider Collaboration EC, 500 KV NESR

2. AIC range M. Bender, P.H. Heenen, P.G. Reinhard Rev. Mod. Phys. 75 (2003) 122 Neutron-skin thickness in Sn isotopes AIC range (1&2) RHB/NL3 (3) RHB/NLSH (3He,t) antiprotons (p,p) normalized to NLSH (4) HFB/SLy4 (5) HFB/SkP

3. Why another method to measure radii? • charge radii can reliably be measured (e.g. (e,e)) • several methods are available for matter / neutron radii • (p,p), (,’), (3He,t), reaction cross section, antiprotonic atoms - BUT: • (p,p) results based on little known p interaction in medium • (,’), (3He,t) results model dependent and normalized to theory • antiprotonic atoms probe density at large distances • We need a method that determines proton and neutron radii • using the same method in the same experiment • independently at the same time with low statistical and systematic errors • solution: • antiproton-ion collisions at high energies measures • rn/rp and (rn-rp)/rn+p • measurement across long isotopic chains (e.g. 104Sn – 134Sn) • provides sensitive test of isospin dependence of effective interaction • in combination with elastic electron scattering data • absolute radii are measured

4. Theoretical cross-sections antiproton-absorption cross section at high energy is proportional to <r2> of the nucleus AIC range normalization at 58Ni AIC range H. Lenske, P. Kienle, nucl-th/0502065

5. Deceleration of antiprotons LSR ER • General needs for AIC: • 70 kV electron cooler in ER • UHV layout of ER for 10-10 mbar (pbar beam lifetime of few days) • transfer line to pbar-ring/ER • polarity switching of CR and RESR within ~ 5 minutes (no particular problem) • Option 1: deceleration in NESR • polarity switching for NESR needed • sensitive collider optics (beam diameters <80 mm) needs to be achieved after each deceleration cycle (once every 1-2 days) • allows NO use of NESR for RIBs parallel to HESR/FLAIR operation

6. Deceleration of antiprotons LSR ER Both options are being considered by accelerator group!! • General needs for AIC: • 70 kV electron cooler in ER • UHV layout of ER for 10-10 mbar (pbar beam lifetime of few days) • transfer line to pbar-ring/ER • polarity switching of CR and RESR within ~ 5 minutes (no particular problem) • Option 2: deceleration in RESR • 70 kV electron cooler needed in RESR • 30MeV extraction cavity in RESR • sensitive collider optics (beam diameters <80 mm) can be optimized and stays unchanged • keep functions of rings separated as much as possible for efficient use of rings (NESR could be used for RIBs during FLAIR operation)

7. Detection of A-1 recoils • A~130: • A & both A-1 nuclei in the acceptance • Schottky method using one ring setting • recoil detection 132Sn 131Sn 132Sn 131In 132Sn 72Ni 71Co 72Ni 71Ni 72Ni • A~70: • A & and one A-1 nucleus in the acceptance • Schottky method using two ring settings • recoil detection 40Ca 39Ca 40Ca 39K 40Ca • A<60: • A-1 nucleus not in the acceptance • recoil detection z

8. example: 68Ni: SFRS yield: 3108 s-1 Np = 106 in < 4h cross-section for production of A-1 nuclei: Total absorption cross-section from reduction of primary ions with mass A ratio of mean square radii (no systematic errors!!) normalized differences of radii Measurement of precise ratios These precise results can be directly compared to theoretical predictions!

9. Measure cross-section of reference isotopes with accurately known charge radius • Measure Luminosity relative to reference measurement 1 2 Obtain rp from elastic electron scattering (ELISe) absolute difference of radii (rn – rp) cross-section for production of A-1 nuclei: Total absorption cross-section from reduction of primary ions with mass A

10. Summary • AIC allows measurement of rms proton and neutron radii independently in the same experiment using the same method (reliable way to determine neutron skins) • radii along isotopic chains are sensitive to isospin dependence of effective nucleon-nucleon interaction • other topics to be investigated: • neutron skins and the transition from halos to skins • shape transitions and shape coexistence • ispspin dependence of the antiproton-nucleon interaction • additional information from AIC • measurement of the momentum distribution of annihilated nucleon • energy dependence of the annihilation cross-section may provide information on density distributions(under investigation) • AIC is complementary to electron scattering • Deceleration of antiprotons in RESR allows for parallel use of NESR for RIBs during HESR/FLAIR operation

11. Antiproton-Ion Collider Collaboration • Spokesperson / Deputy: R. KrückenC / J. ZmeskalA • Project Manager / Deputy: P. KienleC / L. FabbiettiC Krücken, Reiner C Lenske, Horst E Litvinov, Yuri A Marton, Johann B Nolden,Fritz A Ring, Peter C Shatunov, Yuri F Skrinsky, Alexander N. F Suzuki Ken, C Vostrikov, Vladimir A. F Yamaguchi, Takayuki G Widmann,Eberhard B Wycech, Slawomir H Zmeskal, Johann B Beller, Peter A Bosch,FritzA Cargnelli, Michael B Fabbietti, Laura C Faestermann, Thomas C Frankze, Bernhard A Fuhrmann, Hermann B Hayano, Ryugo S.D Hirtl, AlbertB Homolka, Josef C Kienle, Paul B,C Kozhuharov, Christophor A Institute A, Gesellschaft für Schwerionenforschung, Darmstadt, Germany (GSI) Institute B, Stephan Meyer Institut, Vienna, Austria (SMI) Institute C, Technische Universität München, Munich, Germany (TUM) Institute D, University of Tokyo, Tokyo, Japan (UoT) Institute E, Justus-Liebig Universität Giessen., Giessen, Germany (JLU) Institute F, Budker Institute of Nuclear Physics, Novosibirsk, Russia (BINP) Institute G University of Saytama, Saytama, Japan.(UoS) Institute H, Andrzej Soltan Institute for Nuclear Studies, Warsaw, Poland (IPJ)