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Enhancing pbar Yield at FAIR: Sources, Efficiency, and Collection

Explore the yield and collection efficiency of pbar sources at FAIR, CERN, and FNAL, including momentum distributions and cooling processes. Learn about the MARS simulation of the target and horn systems, and potential upgrades with a Li lens. Summary of pbar yield improvements and target considerations for enhanced efficiency.

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Enhancing pbar Yield at FAIR: Sources, Efficiency, and Collection

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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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