Electrostatic Low-Energy Antiproton Recycling Ring Michele Siggel-King on behalf of the Recycling Ring Design Group (Quasar, Musashi & Ullrich groups) 1
Now Motivation Low-Energy Antiproton Research CERN Antiproton Decelerator One possible future: Facility for Antiproton and Ion Research USR Facility for Low energy Antiproton and Ion Research Ultra low energy Storage Ring 2
Motivation is leading developments towards USR ring of the future to enable atomic physics experiments Welsch et al. Nucl. Instr. and Meth. A 546 (2005) 405 USR Electrostatic 300 20 kev bunch length: 1 ns to DC # particles in ring: ~10 7 Papash & Welsch, NIM A, (2010) accepted 3
Motivation Low Energy Antiproton Research Electrostatic Low-Energy Antiproton Recycling Ring Prototype for USR Enable atomic physics crossed-beam studies antiprotons available l from delayed delayed USR 2019, 2020? 4
Installation Configuration ASACUSA Collaboration http://cern.ch/asacusa Accelerating Electrostatic Low-Energy Antiproton Recycling Ring Section CERN Antiproton Decelerator Musashi Trap and beamline beam available from Musashi experimental requirements CERN-AD: S. Baird et al, PAC 97 Conf. Proc. 979 Musashi beamline: Torii et al, AIP Conf. Proc. 273 (2005) 293 5
Antiprotons from Musashi Beamline variable apertures antiprotons t from trap 208 mm tor detec 5 AD shots collected in trap 8 mm 250 ev (1 s) pulse apertures beam defined by 2 apertures 500 000 antiprotons t 5 AD shots ring emittance of 50 mm mrad d (@3 kev) 6
Helium single ionisation cross section CERN (08) this wo 8 cros ss sectio on (10-16 cm 2 ) 0.8 0.4 6 4 2 exptl data (089490) (08,94,90) 12 theoretical ti results (08-96) 100 s counts/hour CERN (94) [2] CERN (90) [1] CP frozen core Mc TDCC Foster et al AOCC: Sahoo et al MEAOCC-2 Igaras IPM-BGM-RESP-2 LTDSE: Schultz an TDDFT/OEP-SIC: T IPM-BGM-RESP-1 MEAOCC-1: Lee et MEHC: Bent et al ( MFIM, 7 cuts: Read IEV: Wehrman et a IPM: wehrman et a H Knudsen et al. PRL 101 (2008) 043201 0 1 10 100 1000 Energy of Antiproton projectile (kev) fundamental atomic physics experiment He antiproton He + + e- 7
Helium single ionisation cross section He + He + p_bar He + e _ + p_bar e- antiproton KE i KE i KE KE KE f ( =0) USR Recycling Ring fully differential cross sections (KE,, ) for each particle partial differential cross sections e.g. (p) or ( ) or (KE) figures from M. McGovern et al., accepted for publication (p) ( ) (KE) 60 kev 12 kev 3 kev 8
Differential Cross Section Measurements positive ion detector Helmholtz coils electrostatic field He + antiproton beam electron detector e- Reaction Microscope 9
Reaction Microscope Resolution (momentum: energy and angular distribution) Resolution is a function of many parameters including size of interaction region divergence of projectile beam union of target gas jet & projectile antiproton beam beam cross sectional area at interaction point: 3 mm diameter beam divergence at interaction ti point: 1 ( 17 mrad) experimental upper limit on the beam emittance of ~26 mm mrad 10
Experimental Set-up most cross-beam experiments: single-pass (use beam only once) Why not incorporate the experiment into the ring? Use beam many times (improvement in luminosity) USR and this ring 11
Electrostatic Antiproton Recycling Ring Fixed-Energy Ring antiproton injection quad singlet quad triplet circumference = 72 7.2 m 90º deflector (250 mm radius) y-corrector x-corrector 12
Ring and Injection Parameters Maximum available intensity Energy of injected particles Antiproton rotation frequency Antiproton rotation period 5x10 5 particles 10-30 kev 193-335 khz 5.2 3.0 s 13
Preliminary Simulation Results 20 LF.LD.LF1 QF1 90 ESD 90 ESD QF1 LF1.LD.LF (m m) 10 y MAD-X Simulation A. Papash x 0 0 1 2 3 distance from interaction region, s (m) at s=0 for an emittance of 10 mm mr x = 10 cm beam diameter = 2.0 x 3.3 mm y = 27 cm beam divergence = ±10 x ±6 mrad = (±0.5 x ±0.3 ) 14
Electrostatic Acceleration Section drift tube -20 kv 0 V Lens -20 kv pulse-on antiproton energy 250 ev acceleration 20 kev H. Knudsen 15
Estimated Experimental Count rates energy of antiprotons (kev) 20 emittance of beam in ring ( mm mrad) 10 number of antiprotons/fill ~155 000 % of 300 000 beam 52% average number of P_bar in ring 58 000 target density (cm -3 ) 5.0 x 10 11 average target length (cm) 0.079 ionisation cross section (cm -3 ) 4.8 x 10-17 detection efficiency 0.4 number of times bunch revolves around ring 6000 number of fills per hour 7 number ionisation events detected per hour 1828 (conservative value) 16
Beam Diagnostics a challenging part of the USR and Recycling Ring project beam diagnostics expertise in Quasar group ultra-short bunches DC beams variable-energy beams low-energy beams ultra-low currents 17
Beam Diagnostics Beam Position Monitor Janusz Ha arasimow wicz J. Harasimowicz et al. Hyperfine Interactions, 194 (2009) 177. Capacitive Pick-up Beam Profile Beam Current Monitor Scintillating screens Faraday Cup 18
Gas Curtain Beam Profile Monitor positive ion detector electrostatic field ion + CCD roscope tion mic reac supersonic expansion to a gas curtain Massimi liano Putigna ano antiproton beam gas curtain Hyperfine Interact (2009) 194:189-193 19
Summary and Outlook Electrostatic Low-Energy Antiproton Recycling Ring to bridge the gap between now and until a new low-energy antiproton facility is operational Capacitive Pick-up Faraday Cup Scintillating screen 20
Summary and Outlook Electrostatic Low-Energy Antiproton Recycling Ring to bridge the gap between now and until a new low-energy antiproton facility is operational Prototype for USR testing and development Enable progress in atomic physics crossed-beam studies partial cross section measurements Presently determining overall feasibility. 21
Acknowledgments Carsten Welsch Alexander Papash Michael Holzscheiter Cockcroft Institute, Daresbury & University of Liverpool, UK Max Planck Institute for Nuclear Physics, Heidelberg, Germany Musashi / ASACUSA collaboration Helge Knudsen Yasunori Yamazaki Hiroyuki Torii Naofumi Kuroda University of Aarhus, Denmark Joachim Ullrich Robert Moshammer MPI Heidelberg 22