Fermilab Accelerator Physics Center Update – Pion Production Sergei Striganov nuSTORM Workshop Fermilab November 21, 2013
OUTLINE • Input parameters update • MARS model verification update • Target parameters update • Target in horn update • Conclusion nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 2 2
Input parameter update -I Very narrow proton beam ( σ =0.15 mm) was used for previous (WS 2012) calculations. More realistic proton beam size is about 1 mm Best results were obtained for gold target inside horn. Experts do not recommend to use heavy target inside horn. Carbon with very high density (3.52 g/cm3) was considered for (WS 2012). Graphite with low density 1.8 g/cm3 is more widely used for pion production. Inconel and tungsten looks like more realistic target material than gold. nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 3 3
Input parameter update -II Proton beam energy was 60 GeV in last year study. Yields with 120 GeV proton beam should be studied now. Magnetic field inside horn material and pion/proton interaction with inner/outer conductors should be taken into account Horn current should not exceed 230 kA (300 kA in last year study) MARS code prediction of 5 GeV/c pion production at 120 GeV should be verified against data nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 4 4
MARS verification Ed 3 σ /dp 3 (mb/GeV 2 /c 3 ) We are going to calculate 10 3 p T (GeV/c) yield of pion within small momentum bin around 5 ν STORM region 0.1 GeV/c produced by 120 GeV/c protons on thick 0.3 target using MARS model. 10 2 How well MARS model 0.5 agrees with experiment in this region? 0.7 We have a lot of applicable 10 data for light target (Be, C) There are only few proper measurement for heavy -0.1 0 0.1 0.2 0.3 0.4 0.5 nuclei x f Positive pion production in proton-carbon interaction at 158 GeV/c nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 5 5
MARS verification - II Red lines - MARS-incl Blue lines - MARS-LAQGSM 3.5 d σ /dp in 1/(GeV/c) 1.4 3 0-20 mrad 20-40 mrad 1.2 2.5 1 2 0.8 1.5 0.6 1 0.4 0.5 0.2 0 0 0 2 4 6 8 0 5 10 15 20 momentum in GeV/c momentum in GeV/c d σ /dp in 1/(GeV/c) 14 5 40-60 mrad 60-100 mrad 12 4 10 3 8 6 2 4 1 2 0 0 0 5 10 15 20 0 5 10 momentum in GeV/c momentum in GeV/c π + production in proton-carbon interaction at 31 GeV/c nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 6
MARS verification - III Red line – MARS model at 19.2 GeV/c, blue line – MARS model at 450 GeV/c Ed 3 σ /dp 3 (mb/GeV 2 /c 3 ) Ed 3 σ /dp 3 (mb/GeV 2 /c 3 ) 450 GeV/c - SPY collaboration 450 GeV/c - SPY collaboration 400 GeV/c - Atherton et al 400 GeV/c - Atherton et al 10 4 10 4 400 GeV/c - Antreasyan et al 400 GeV/c - Antreasyan et al 100 GeV/c - Barton et al 100 GeV/c - Barton et al p t = 0 GeV/c p t = 0 GeV/c 10 3 10 3 24 GeV/c - Eichten et al 24 GeV/c - Eichten et al 19.2 GeV/c - Allaby et al 19.2 GeV/c - Allaby et al 67 GeV/c - Bozhko et al 67 GeV/c - Bozhko et al*2 10 2 10 2 10 10 p t = 0.3 GeV/c *10 −1 p t = 0.3 GeV/c 1 1 -1 -1 10 10 p t = 0.5 GeV/c *10 −2 -2 -2 x lab = 5/120 10 10 p t = 0.5 GeV/c -3 -3 10 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 x lab = p lab /p o x lab = p lab /p o π + production in proton beryllium interaction π + production in proton beryllium interaction nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 7
MARS verification - IV Red line – MARS model at 19.2 GeV/c, blue line – MARS model at 450 GeV/c Ed 3 σ /dp 3 mb/GeV 2 Ed 3 σ /dp 3 mb/GeV 2 24 GeV/c Eichten et al 24 GeV/c Eichten et al MARS 70 GeV/c 67 GeV/c Bozhko et al (extr) 67 GeV/c Bozhko et al (extr)*2 70 GeV/c Barkov et al 70 GeV/c Barkov et al (extr) 10 4 10 4 158 GeV/c NA49 158 GeV/c NA49 450 GeV/c NA44 450 GeV/c NA44 MARS 24 GeV/c 10 3 10 3 5 GeV/120 GeV 10 2 10 2 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3 0.4 0.5 x lab = p lab /p o x lab = p lab /p o π + production in proton-lead interaction at 0 degree π + production in proton-lead interaction at 0 degree nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 8
Simulation procedure For given material and beam size we need to determine optimal target length, radius and position inside horn. From previous study we know that optimal target radius is about 3 sigma of proton beam. Two optimization parameters are considered for positive pion with momentum 5±0.5 GeV/c: number of particles inside 20 cm radius (most of pion in this momentum range) and pions inside admittance = 0.2 cm rad. David Neuffer estimates this as smallest value in ring. For fixed admittance we determine values of Twiss parameters β and α which corresponds to maximal number of pions. This yields correspond to maximal and minimal estimates of captured pions numbers. nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 9
Phase distribution at 1 cm after target target - graphite, 95 cm length, 3 mm radius target - inconel, 38 cm length, 3 mm radius target - tungsten, 29 cm length, 3 mm radius 120 GeV proton, σ =1 mm 120 GeV proton, σ =1 mm 120 GeV proton, σ =1 mm π + - δ p/p=0.1, ε = 2 mm rad, β =282.5 cm, α =-4 π + - δ p/p=0.1, ε = 2 mm rad, β =87.5 cm, α =-3 + - δ p/p=0.1, ε = 2 mm rad, β =82.5 cm, α =-3.5 π -2 -2 -2 10 10 10 dx/ds dx/ds dx/ds 0.15 0.15 0.15 0.1 0.1 0.1 -3 -3 -3 10 10 10 0.05 0.05 0.05 -4 -4 0 10 -4 0 10 0 10 -0.05 -0.05 -0.05 -5 -5 10 -5 10 10 -0.1 -0.1 -0.1 -0.15 -6 -0.15 -6 10 -0.15 -6 -10 -8 -6 -4 -2 0 2 4 6 8 10 10 -10 -8 -6 -4 -2 0 2 4 6 8 10 10 -10 -8 -6 -4 -2 0 2 4 6 8 10 x (cm) x (cm) x (cm) Ɛ =2 mm: yield = 0.099 Ɛ =2 mm: yield = 0.164 Ɛ =2 mm: yield = 0.175 r< 20 cm: yield = 0.194 r< 20 cm: yield = 0.235 r< 20 cm: yield = 0.241 nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 10
Target material dependence: no gain from very heavy target? π + /POT π + /POT 0.04 1 0.035 95 cm graphite 95 cm graphite 38 cm inconel 38 cm inconel 0.03 29 cm tungsten 29 cm tungsten -1 10 0.025 0.02 -2 10 0.015 0.01 angle < 120 mrad -3 0.005 10 0 5 10 15 20 25 30 35 40 45 2 3 4 5 6 7 8 9 10 π - /POT π - /POT momentum (GeV/c) momentum (GeV/c) 0.04 1 0.035 0.03 -1 10 0.025 0.02 -2 10 0.015 0.01 -3 0.005 10 0 5 10 15 20 25 30 35 40 45 2 3 4 5 6 7 8 9 10 momentum (GeV/c) momentum (GeV/c) nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 11
Target radius@length dependence: opposite radial dependence for heavy and light targets! π + yield/POT in proton-gold interaction at 60 GeV/c π + yield/POT in proton-graphite interaction at 60 GeV/c 0.16 0.15 3.3 mm target radius, σ p =1.1 mm 3 mm target radius, σ p =1 mm 0.45 mm target radius, σ p =0.15 mm 0.14 0.45 mm target radius, σ p =0.15 mm 0.14 0.13 0.12 0.12 0.1 0.11 0.08 0.1 r < 20cm r < 20cm 0.09 0.06 0.08 6 8 10 12 14 16 18 20 22 24 60 70 80 90 100 110 120 target length (cm) target length (cm) 0.16 0.07 0.068 0.14 0.066 0.064 0.12 0.062 0.06 0.1 0.058 0.08 0.056 0.054 ε =0.2 cm rad ε =0.2 cm rad 0.06 0.052 0.05 6 8 10 12 14 16 18 20 22 24 60 70 80 90 100 110 120 target length (cm) target length (cm) nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 12
120 GeV proton, 5 +-0.5 GeV/c pion, 3 mm target radius nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 13
Target position inside horn: send negative 5 Gev/c pion from opposite direction to find horn focus for different magnetic field 230 kA – reasonable upgrade 185 kA – NuMI default nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 14
Realistic and simplified horn description: simplified - magnetic field only, “realistic” - interaction with conductors and field in conductors taken into account. “realistic”: yield=0.114 pi+/POT simple: yield=0.122 pi+/POT nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 15
95 cm graphite target. Dependence of pion beam parameters on target center shift from upstream horn end. dp/p=10% pi+/POT pi+/POT 0.2 0.09 1cm after 1.9m horn 0.19 1cm after 3m horn 0.18 0.088 1m after 3m horn 0.17 0.16 0.086 0.15 0.14 0.084 0.13 ε = 2 mm rad 0.12 0.082 r < 20cm 0.11 0.1 0.08 -10 0 10 -10 0 10 distance from upstream horn end distance from upstream horn end 550 0.6 beta (cm) alpha 500 0.4 450 0.2 400 -0 350 -0.2 300 -0.4 250 -0.6 -10 0 10 -10 0 10 distance from upstream horn end distance from upstream horn end nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 16
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