HARP 5% Ta Target Results compared to MARS15
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Stephen Brooks / [email protected] UKNF meeting, Oxford, September HARP 5% Ta Target Results compared to MARS15
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HARP 5% Ta Target Results compared to MARS15. HARP Detector Ranges. 250
Transcript of HARP 5% Ta Target Results compared to MARS15
Stephen Brooks / [email protected]
UKNF meeting, Oxford, September 2008
HARP 5% Ta Target Results compared to MARS15
Stephen Brooks / [email protected] meeting, Oxford, September 2008
HARP Detector Ranges
LAS
Forward calorimeter
250<p_T<500 MeV/c(0.35)<theta<0.95 radians
Stephen Brooks / [email protected] meeting, Oxford, September 2008
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 / [email protected]
UKNF meeting, Oxford, September 2008
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 / [email protected] meeting, Oxford, September 2008
Sanford-Wang Formula
• Originally for collisions on Be at ~10GeV
• (cos )c8 messes up for >90°• Replace by exp(c8 (cos() - 1)) when including LAS
Stephen Brooks / [email protected] meeting, Oxford, September 2008
Thin-to-Thick Estimation
• Assuming no tertiaries/reabsorption
• Thin target - multiply by A
• Thick target - use corrected formula:
…for target length L, interaction length • L = 20cm, Ta = 11.18cm in what follows
A (1 − e−L/) / L
Stephen Brooks / [email protected] meeting, Oxford, September 2008
Stephen Brooks / [email protected] meeting, Oxford, September 2008
Analysis Summary (so far)
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0 2 4 6 8 10 12
Proton Energy (GeV)
Us
efu
l p
i/(p
.Ge
V)
pi+ partial
pi- partial
pi+ extended
pi- extended
pi+ fwd. fit
pi- fwd. fit
Stephen Brooks / [email protected] meeting, Oxford, September 2008
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)
