Recycling Ring. on behalf of the Recycling Ring Design Group (Quasar, Musashi & Ullrich groups) TCP 2010 Conference 12 April 2010

Transcription

1 Electrostatic Low-Energy Antiproton Recycling Ring Michele Siggel-King on behalf of the Recycling Ring Design Group (Quasar, Musashi & Ullrich groups) 1

2 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

3 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 kev bunch length: 1 ns to DC # particles in ring: ~10 7 Papash & Welsch, NIM A, (2010) accepted 3

4 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

5 Installation Configuration ASACUSA Collaboration 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

6 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 antiprotons t 5 AD shots ring emittance of 50 mm mrad d (@3 kev) 6

7 Helium single ionisation cross section CERN (08) this wo 8 cros ss sectio on (10-16 cm 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) Energy of Antiproton projectile (kev) fundamental atomic physics experiment He antiproton He + + e- 7

8 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

9 Differential Cross Section Measurements positive ion detector Helmholtz coils electrostatic field He + antiproton beam electron detector e- Reaction Microscope 9

10 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

11 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

12 Electrostatic Antiproton Recycling Ring Fixed-Energy Ring antiproton injection quad singlet quad triplet circumference = m 90º deflector (250 mm radius) y-corrector x-corrector 12

13 Ring and Injection Parameters Maximum available intensity Energy of injected particles Antiproton rotation frequency Antiproton rotation period 5x10 5 particles kev khz s 13

14 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 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

15 Electrostatic Acceleration Section drift tube -20 kv 0 V Lens -20 kv pulse-on antiproton energy 250 ev acceleration 20 kev H. Knudsen 15

16 Estimated Experimental Count rates energy of antiprotons (kev) 20 emittance of beam in ring ( mm mrad) 10 number of antiprotons/fill ~ % of beam 52% average number of P_bar in ring target density (cm -3 ) 5.0 x average target length (cm) ionisation cross section (cm -3 ) 4.8 x 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

17 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

18 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

19 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:

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 Capacitive Pick-up Faraday Cup Scintillating screen 20

21 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

22 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