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HARP 5% Ta Target Results compared to MARS15

HARP 5% Ta Target Results compared to MARS15. HARP Detector Ranges. 250<p_T<500 MeV/c (0.35)<theta<0.95 radians. LAS. Forward calorimeter. Pion Cross-section Totals. Quantitative Comparison. Total production: agreement at ~20% level MARS15 makes up to 16% too few pi+

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HARP 5% Ta Target Results compared to MARS15

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  1. HARP 5% Ta Target Results compared to MARS15 Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  2. HARP Detector Ranges 250<p_T<500 MeV/c (0.35)<theta<0.95 radians LAS Forward calorimeter Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  3. Pion Cross-section Totals Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  4. Quantitative Comparison • Total production: agreement at ~20% level • MARS15 makes up to 16% too few pi+ • Up to 24% too many pi- (same way at all E) • In cut of interest: • Pi+ closer, deviations under 13% • Pi- worse, MARS15 overestimating by ~30% • Up to 44% • Remember that MARS15-G4 was factor 2! Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  5. Forward vs. Backward pi+ above pi- Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  6. Negatives Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  7. Positives Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  8. Sign ratio! (Negativity) Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  9. Combining HARP data & fits with Muon Yield Probabilities Michel Sorel (FNAL), Jaap Panman (CERN) performed original Forward Spectrometer fits John Back made ISS front-end probability map Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  10. Sanford-Wang Formula • Originally for collisions on Be at ~10GeV • (cos q)c8 messes up for q>90° • Replace by exp(c8 (cos(q) - 1)) when including LAS Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  11. Thin-to-Thick Estimation • Assuming no tertiaries/reabsorption • Thin target - multiply s by rA • Thick target - use corrected formula: …for target length L, interaction length l • L = 20cm, lTa = 11.18cm in what follows rA l (1 − e−L/l) / L Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  12. Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  13. Analysis Summary (so far) Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

  14. Future Work • Produce fits to both forward spectrometer and LAS at the same time (in progress) • Investigate models besides Sanford-Wang • Re-evaluate with best fits • Including secondary processes is the only way to get the thick target totally right, requires this data integrated into MARS code etc. (pi + N  X + pi data useful too) Stephen Brooks / s.j.brooks@rl.ac.uk UKNF meeting, Oxford, September 2008

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