[PPT] - Fermilab Accelerator Physics Center Update Pion Production PowerPoint Presentation

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Update – Pion Production

nuSTORM Workshop Fermilab November 21, 2013

Sergei Striganov Fermilab Accelerator Physics Center

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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

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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

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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

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MARS verification

We are going to calculate yield of pion within small momentum bin around 5 GeV/c produced by 120 GeV/c protons on thick target using MARS model. How well MARS model agrees with experiment in this region? We have a lot of applicable data for light target (Be, C) There are only few proper measurement for heavy nuclei

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov

Positive pion production in proton-carbon interaction at 158 GeV/c xf Ed3σ/dp3 (mb/GeV2/c3)

pT (GeV/c) 0.1 0.3 0.5 0.7 νSTORM region

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MARS verification - II

π+ production in proton-carbon interaction at 31 GeV/c momentum in GeV/c dσ/dp in 1/(GeV/c)

0-20 mrad Red lines - MARS-incl Blue lines - MARS-LAQGSM

momentum in GeV/c

20-40 mrad

momentum in GeV/c dσ/dp in 1/(GeV/c)

40-60 mrad

momentum in GeV/c

60-100 mrad

0.2 0.4 0.6 0.8 1 1.2 1.4 2 4 6 8 0.5 1 1.5 2 2.5 3 3.5 5 10 15 20 1 2 3 4 5 5 10 15 20 2 4 6 8 10 12 14 5 10

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MARS verification - III

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 7

Red line – MARS model at 19.2 GeV/c, blue line – MARS model at 450 GeV/c

π+ production in proton beryllium interaction xlab = plab/po Ed3σ/dp3 (mb/GeV2/c3) 450 GeV/c - SPY collaboration 400 GeV/c - Atherton et al 400 GeV/c - Antreasyan et al 100 GeV/c - Barton et al 67 GeV/c - Bozhko et al 24 GeV/c - Eichten et al 19.2 GeV/c - Allaby et al

pt = 0.5 GeV/c *10−2 pt = 0.3 GeV/c *10−1 pt = 0 GeV/c

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1 10 10 2 10 3 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 π+ production in proton beryllium interaction xlab = plab/po Ed3σ/dp3 (mb/GeV2/c3)

xlab= 5/120

450 GeV/c - SPY collaboration 400 GeV/c - Atherton et al 400 GeV/c - Antreasyan et al 100 GeV/c - Barton et al 67 GeV/c - Bozhko et al*2 24 GeV/c - Eichten et al 19.2 GeV/c - Allaby et al

pt = 0.5 GeV/c pt = 0.3 GeV/c pt = 0 GeV/c

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MARS verification - IV

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Red line – MARS model at 19.2 GeV/c, blue line – MARS model at 450 GeV/c

π+ production in proton-lead interaction at 0 degree xlab = plab/po Ed3σ/dp3 mb/GeV2 24 GeV/c Eichten et al 70 GeV/c Barkov et al 67 GeV/c Bozhko et al (extr) 158 GeV/c NA49 450 GeV/c NA44 10 2 10 3 10 4 0.1 0.2 0.3 0.4 0.5 π+ production in proton-lead interaction at 0 degree xlab = plab/po Ed3σ/dp3 mb/GeV2 24 GeV/c Eichten et al 70 GeV/c Barkov et al (extr) 67 GeV/c Bozhko et al (extr)*2 158 GeV/c NA49 450 GeV/c NA44

5 GeV/120 GeV MARS 70 GeV/c MARS 24 GeV/c

10 2 10 3 10 4 0.1 0.2 0.3 0.4 0.5

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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

SLIDE 10

Phase distribution at 1 cm after target

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Ɛ=2 mm: yield = 0.099 r< 20 cm: yield = 0.194 Ɛ=2 mm: yield = 0.164 r< 20 cm: yield = 0.235 Ɛ=2 mm: yield = 0.175 r< 20 cm: yield = 0.241

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x (cm) dx/ds

target - graphite, 95 cm length, 3 mm radius 120 GeV proton, σ=1 mm π+ - δp/p=0.1, ε= 2 mm rad, β=282.5 cm, α=-4

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x (cm) dx/ds

target - inconel, 38 cm length, 3 mm radius 120 GeV proton, σ=1 mm π+ - δp/p=0.1, ε= 2 mm rad, β=87.5 cm, α=-3

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x (cm) dx/ds

target - tungsten, 29 cm length, 3 mm radius 120 GeV proton, σ=1 mm π

+ - δp/p=0.1, ε= 2 mm rad, β=82.5 cm, α=-3.5

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Target material dependence: no gain from very heavy target?

momentum (GeV/c)

π+/POT 95 cm graphite 29 cm tungsten 38 cm inconel

momentum (GeV/c)

π-/POT

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1 5 10 15 20 25 30 35 40 45 momentum (GeV/c)

π+/POT 95 cm graphite 29 cm tungsten 38 cm inconel angle < 120 mrad

momentum (GeV/c)

π-/POT

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 2 3 4 5 6 7 8 9 10 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 2 3 4 5 6 7 8 9 10

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 11

SLIDE 12

Target radius@length dependence:

pposite radial dependence for heavy and light targets!

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 12

r < 20cm

target length (cm) 3.3 mm target radius, σp=1.1 mm 0.45 mm target radius, σp=0.15 mm

π+ yield/POT in proton-gold interaction at 60 GeV/c

target length (cm)

ε=0.2 cm rad

0.06 0.08 0.1 0.12 0.14 0.16 6 8 10 12 14 16 18 20 22 24 0.06 0.08 0.1 0.12 0.14 0.16 6 8 10 12 14 16 18 20 22 24

r < 20cm

target length (cm) 3 mm target radius, σp=1 mm 0.45 mm target radius, σp=0.15 mm

π+ yield/POT in proton-graphite interaction at 60 GeV/c

target length (cm)

ε=0.2 cm rad

0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 60 70 80 90 100 110 120 0.05 0.052 0.054 0.056 0.058 0.06 0.062 0.064 0.066 0.068 0.07 60 70 80 90 100 110 120

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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

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Target position inside horn: send negative 5 Gev/c pion from opposite direction to find horn focus for different magnetic field

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185 kA – NuMI default 230 kA – reasonable upgrade

SLIDE 15

Realistic and simplified horn description: simplified - magnetic field only, “realistic”

interaction with

conductors and field in conductors taken into account.

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 15

simple: yield=0.122 pi+/POT “realistic”: yield=0.114 pi+/POT

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95 cm graphite target. Dependence of pion beam parameters on target center shift from upstream horn end. dp/p=10%

distance from upstream horn end

pi+/POT

1cm after 1.9m horn 1cm after 3m horn 1m after 3m horn

r < 20cm

distance from upstream horn end

pi+/POT ε= 2 mm rad

distance from upstream horn end beta (cm) distance from upstream horn end alpha 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2

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50 cm inconel target. Dependence of pion beam parameters on target center shift from upstream horn end. dp/p=10%

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distance from upstream horn end

pi+/POT

1cm after 1.9m horn 1cm after 3m horn 1m after 3m horn

r < 20cm

distance from upstream horn end

pi+/POT ε= 2 mm rad

distance from upstream horn end beta (cm) distance from upstream horn end alpha 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 10 20 0.09 0.095 0.1 0.105 0.11 0.115 0.12 0.125 0.13 10 20 500 600 700 800 900 1000 1100 1200 10 20

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29 cm tungsten target. Dependence of pion beam parameters on target center shift from upstream horn end. dp/p=10%

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 18

distance from upstream horn end

pi+/POT

1cm after 1.9m horn 1cm after 3m horn 1m after 3m horn

r < 20cm

distance from upstream horn end

pi+/POT ε= 2 mm rad

distance from upstream horn end beta (cm) distance from upstream horn end alpha 0.1 0.12 0.14 0.16 0.18 0.2 0.22

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Phase distribution after horn – graphite target

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After NuMI horn: Ɛ=2 mm: yield = 0.085 r< 20 cm: yield = 0.137 1 m after NuMI horn: Ɛ=2 mm: yield = 0.085 r< 20 cm: yield = 0.133

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Phase distribution after horn – inconel target

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov 20

After NuMI horn: Ɛ=2 mm: yield = 0.122 r< 20 cm: yield = 0.162 1 m after NuMI horn: Ɛ=2 mm: yield = 0.120 r< 20 cm: yield = 0.157

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CONCLUSION

Dependence of 5 GeV/c pi+ yield on target length, radius, material and position inside horn was studied. Beam energy – 120 GeV, beam radius –

1mm. Horn current-

230 kA. Optimal target size and position were determined for inconel, tungsten and graphite. Yield rises with target length. But slope is very small. Dependence on target position inside horn is rather weak. Dependence of yield on target radius is opposite for heavy and light targets. Number of pions inside of 20 cm radius is about 0.13 pi+/POT for 95 cm carbon target and dp/p=10%. It rises on about 20% for 50cm inconel target, but only 10% larger for 29 cm tungsten target. Number of pions inside of 2 mm rad admittance is about 0.085 pi+/POT for graphite and dp/p=10%. It is about 40% larger for inconel and 30% larger for tungsten. Simulations confirm, that yield is linearly raised with dp/p (at least up to 20%) Switch to “realistic” horn model slightly decreases predicted yield, but change in shape of distribution is not so marginal. Inclusive MARS model agrees well with data on carbon and beryllium in nuSTORM range

f interest. MIPP and NA61/SHINE measurements for medium and heavy nucleus will be

published during following one/two years. It could clarify precision of MARS prediction for such target.

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov

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SLIDE 23

BACKUP slides

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CONCLUSIONS of nuSTORM 2012 Workshop

We could get about 0.11 π+/POT and 0.09 π-/POT with 5 ± 10% GeV/c momentum from gold target at 60 GeV into 2000 mm mrad acceptance with ideal capture. Yield for carbon is about 2 times lower at this energy. We could get about 0.006 π+/POT and 0.0035 π-/POT with 3 ± 10% GeV/c momentum from gold target at 8 GeV into 2000 mm mrad acceptance with ideal capture. Yield has weak dependence on target material at this energy. Pion capture using lithium lens looks like problematic due to large radius of pion beam. Pion capture using horn looks like reasonable. Without optimization of inner surface shape it is possible to get 0.082 π+/POT with 5 ± 0.5 GeV/c momentum using existing NuMI horn at 300kA current. Measurements of charged pion production from heavy target are in 30% agreement with MARS prediction. New measurements of MIPP and NA61/SHINE will help to specify absolute normalization of above simulation. Could we use large Z target inside horn at 60 GeV? Could we optimize horn shape to get better transmission factor? Very low energy horn with conical shape (Beams-doc-724) provides transmission factor about 0.9, but β = 2000 cm looks like too large.

nuSTORM Workshop – Fermilab, Nov. 21, 2013 Pion Production - S.I. Striganov

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pT

2 (GeV/c)2

π+/POT 95 cm graphite 29 cm tungsten 38 cm inconel

pT

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π-/POT

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Target radius

nuSTORM meeting – Fermilab, Jan. 18, 2013 Target update - S.I. Striganov 26

20 cm gold target 95 cm graphite target

r < 20cm

R - target radius (cm) 1 cm after target , σp = R/3 250 cm horn , σp = R/3 350 cm horn, σp = R/3

π+ yield/POT in proton-gold interaction at 60 GeV/c

R - target radius (cm)

ε=0.2 cm rad

0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

r < 20cm

R - target radius (cm) 1 cm after target, σp = R/3 250 cm horn, σp = R/3 350 cm horn, σp = R/3

π+ yield/POT in proton-graphite interaction at 60 GeV/c

R - target radius (cm)

ε=0.2 cm rad

0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5