Fermilab Accelerator Physics Center Update Pion Production - PowerPoint PPT Presentation

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