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pbar Yield and Collection Efficiency of the FAIR pbar Source

pbar Yield and Collection Efficiency of the FAIR pbar Source. FAIR – CERN –FNAL pbar sources angular and momentum distributions after the target pbar collection with a magnetic horn MARS simulation of the system target – horn pbar collection with a Li lens summary.

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pbar Yield and Collection Efficiency of the FAIR pbar Source

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  1. pbar Yield and Collection Efficiencyof the FAIR pbar Source • FAIR – CERN –FNAL pbar sources • angular and momentum distributions after the target • pbar collection with a magnetic horn • MARS simulation of the system target – horn • pbar collection with a Li lens • summary

  2. FAIR/CERN/FNAL pbar Sources Increases the pbar yield by  50 % Design goal: Luminosity for HESR experiments = 2 × 1032 cm-2s-1Max. pbar scattering cross section 100 mb (H2 target) → pbar consumption: 2 × 107 s-1cycle time 10 s (cooling time in the CR)overallpbar yield: 5 × 10-6 pbar/p (based on CERN data) → 4 × 1013 ppp (FAIR BTR) FAIR Collector ring will be operated at h = 1, CERN ring was operated at h = 6 Time needed for stochastic cooling in CR (AC), upgrade possible K. Knie, PBAR@FAIR, 4.12.2007

  3. Overview 29 GeV p from SIS 100 pbar separator240 p mm mradp = 3.82 GeV/cDp/p = 3% target +collector K. Knie, PBAR@FAIR, 4.12.2007

  4. pbar Distribution After the Target R.P. Duperray et al., Phys. Rev. D 68, 094017 (2003) Fit to all available experimental results, especially at lower proton energies K. Knie, PBAR@FAIR, 4.12.2007

  5. Collecting pbars:The Magnetic Horn B  1/r primary beam does not hit the horn reaction products K. Knie, PBAR@FAIR, 4.12.2007

  6. Collecting pbars:The Magnetic Horn CERN ACOL Horn, I = 400 kA K. Knie, PBAR@FAIR, 4.12.2007

  7. Yield vs Target Length target target p pbar sabs(p) sprod(pbar) sabs(pbar) Absorption cross sections: S.P. Denisov et al., Nucl. Phys. B 61, 62 (1973) Production cross sections: R.P. Duperray et al., Phys. Rev. D 68, 094017 (2003) K. Knie, PBAR@FAIR, 4.12.2007

  8. Yield vs Target Length target target p pbar sabs(p) sprod(pbar) sabs(pbar) K. Knie, PBAR@FAIR, 4.12.2007

  9. Yield vs Target Length target p pbar sabs(p) sprod(pbar) sabs(pbar) K. Knie, PBAR@FAIR, 4.12.2007

  10. Yield vs Target Length target p pbar sabs(p) sprod(pbar) sabs(pbar) K. Knie, PBAR@FAIR, 4.12.2007

  11. MARS Simulation of the pbar Yields pbars in the ellipse yield = primary protons K. Knie, PBAR@FAIR, 4.12.2007

  12. MARS Simulation of the pbar Yields p pbar Ir: sp = 1.8 bspbar=2.0 b C: spbar=0.42 b K. Knie, PBAR@FAIR, 4.12.2007

  13. Temperature Increase in the Target cIr = 130 J kg-1 K-1 cCu = 385 J kg-1 K-1 cNi = 440 J kg-1 K-1 K. Knie, PBAR@FAIR, 4.12.2007

  14. Temperature Increase in the Target K. Knie, PBAR@FAIR, 4.12.2007

  15. Li Lens – A Possible Upgrade? Lithium sabs(pbar) = 176 mbarn r(Li) = 0.535 g cm-3 l(lens) = 140 mm T = 89 % Copper sabs(pbar) = 831 mbarn r(Cu) = 8.96 g cm-3 l(lens) = 140 mm T = 37 % massive Li cylinder B  r primary beamgoes through the Li reaction products K. Knie, PBAR@FAIR, 4.12.2007

  16. Li Lens – A Possible Upgrade? q < 100 mrad can be collected I = 1 MA (I ~ r²) Distance target center - lens: 100 mm technically challenging / expensive 20 mrad < q < 80 mrad can be collected I = 0.4 MA Distance target center - lens: 220 mm more simple and reliable, less expensive K. Knie, PBAR@FAIR, 4.12.2007

  17. Li Lens – A Possible Upgrade? K. Knie, PBAR@FAIR, 4.12.2007

  18. Li Lens – A Possible Upgrade? K. Knie, PBAR@FAIR, 4.12.2007

  19. Li Lens – A Possible Upgrade? K. Knie, PBAR@FAIR, 4.12.2007

  20. Li Lens – A Possible Upgrade? Experimental data from CERN:A 34 mm/1.1 MA lens gave a 20% higher yieldcompared to a 0.4 MA horn: K. Knie, PBAR@FAIR, 4.12.2007

  21. Overall Yield Yield → 240 p mm mrad, Dp/p = 3 %: 20 × 10-6 pbar/p eSeparator 80 % 16 × 10-6pbar/p eCR70 % 11 × 10-6pbar/p eRESR70 % 8 × 10-6pbar/p "The ... yields agree with the calculations except of an unexplained factor of 1.5" (Autin et al., EPAC 1990)5 × 10-6pbar/p (?) exp. CERN (horn) 4.6× 10-6 pbar/p CERN: design 50% operation 63%→91% 2 × 1013 ppp, 0.1 Hz (1.0 - 1.6 ) × 107 pbar/sneeded for LHESR = 2× 1032cm-2s-12.0 × 107 pbar/s K. Knie, PBAR@FAIR, 4.12.2007

  22. Summary • Ni target: Less secondary particles, higher heat capacity compared to Ir or W:A Ni target can tolarate a 4 times higher beam intensity than an Ir target. • Smaller beamspot possible for Ni: Overcompensates the negative effect of Ni's lower density and therefore higher target length. • Simulations give a yield of 2 × 10-5 pbar/p (only target/horn):11 cm Ni target (d = 3 mm) in a graphite container, 0.62 mm (rms)beamspot. No target melting up to 4 × 1013 ppp. A dramatic improvement of this yield is not possible (without increasing the momentum acceptance of separator/CR). • This corresponds to an overall yield of 8 × 10-6 pbar/p (or somewhat below):eSepartor  80%, eCR  eRESR  70% • Simulations show no significant improvement with a Li lens instead of a horn:A Li lens' collection efficiency is more sensitive to the target geometry. Ir target: at high beam intensities, the beamspot needs to be very large. Ni target: needs to be relatively long. • The repition rate is not limited by the target, but by the CR's cooling timeTime averaged, less than 1 kW beam power is deposited in the target at 0.1 Hz. K. Knie, PBAR@FAIR, 4.12.2007

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