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Target/Beam InteractionMICE Target Workshop – RAL

8/1/2009

M. Apollonio, A. Dobbs - IC

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Motivations:• optimise secondary production minimising

dangerous losses in ISIS

• assess better orientation/shape of the shaft for secondary production

• a work at “four hands”:• A. Dobbs, ORBIT simulation of ISIS ring /

interaction with target / comparison with data taken from MICE shifts,

• MA, G4Beamline simulation of secondary production with a set of shafts

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ORBIT Results A. Dobbs

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- overview of results obtained from simulating beam loss in ISIS synchrotron- using code ORBIT - emphasis to loss caused by MICE target - results for 3 target orientations: • long-thin • short-fat • tilted or parallel to the MICE beamline- 2 target sizes are used: • 10mm x 1mm and • 1mm x 1mm- dip depths ranging from 27mm to 24mm above beam axis are shown.

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Target Orientations (variable depths)

•“Short-Fat” – 1mm along z – axis, 10mm along x - axis

• “Long-Thin” – 10mm along z – axis, 1mm along x – axis (true orientation)

•“Reduced” – 1mm along z – axis, 1mm along x - axis

x

y

s

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Model

The MICE target is modelled as a block of iron inserted into the ISIS beam 2ms before extraction, sitting at a position of ~115m around the synchrotron ring. The target is also currently modelled as being static.

Work is being done about the possibility of improving the model to make the target titanium and dynamic.

NB: ORBIT phys.models elastic/inelastic/nuclear

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TGT

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Results• 2D histograms showing number of particles lost from the beam as a function of time in an ISIS spill and the position in the synchrotron in which they were lost. • Further a table is also presented for each target configuration, showing the number of “hits” (intersections of the volume) in the MICE target, for the last 2ms of the ISIS spill• The tables also give the number of particles “absorbed” by the target i.e. turned into lost particles by their interaction with the target.

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Injection losses MICE target

losses MICE target

losses

Short-Fat: 27mm above axis, -1 to 10ms

zoom last 2 ms

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Short-Fat: 27mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 1986 14 0.00704935

Mice2 11110 115.226 0 0 0

Mice3 11120 115.227 0 0 0

Mice4 11130 115.228 0 0 0

Mice5 11140 115.229 0 0 0

Mice6 11150 115.23 0 0 0

Mice7 11160 115.231 0 0 0

Mice8 11170 115.232 0 0 0

Mice9 11180 115.233 0 0 0

Mice10 11190 115.234 0 0 0

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Long-Thin: 27mm above axis, -1 to 10ms(NB: present config)

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Long-Thin: 27mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 613 3 0.00489396

Mice2 11110 115.226 615 0 0

Mice3 11120 115.227 617 0 0

Mice4 11130 115.228 617 0 0

Mice5 11140 115.229 614 1 0.00162866

Mice6 11150 115.23 609 0 0

Mice7 11160 115.231 601 0 0

Mice8 11170 115.232 592 1 0.00168919

Mice9 11180 115.233 581 0 0

Mice10 11190 115.234 568 0 0

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Long-Thin: 26mm above axis, -1 to 10ms

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Long-Thin: 26mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 1045 6 0.00574163

Mice2 11110 115.226 1043 2 0.00191755

Mice3 11120 115.227 1051 0 0

Mice4 11130 115.228 1042 0 0

Mice5 11140 115.229 1038 0 0

Mice6 11150 115.23 1020 0 0

Mice7 11160 115.231 1003 0 0

Mice8 11170 115.232 995 0 0

Mice9 11180 115.233 990 0 0

Mice10 11190 115.234 966 1 0.0010352

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Long-Thin: 27mm above axis, 250 rotation, -1 to 10ms

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Long-Thin: 27mm above axis, 250 rotation, 8 to 10ms

NB At present there remains an ambiguity in the direction of the rotation, clockwise or anti-clockwise. If / when this is resolved it will be published in an updated version of this document.

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 205 0 0

Mice2 11110 115.226 202 0 0

Mice3 11120 115.227 181 1 0.00552486

Mice4 11130 115.228 191 0 0

Mice5 11140 115.229 197 1 0.00507614

Mice6 11150 115.23 215 2 0.00930233

Mice7 11160 115.231 227 1 0.00440529

Mice8 11170 115.232 214 0 0

Mice9 11180 115.233 203 0 0

Mice10 11190 115.234 0 0 0

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Reduced: 27mm above axis, -1 to 10ms

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Reduced (1mm^2): 27mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 1044 6 0.00574713

Mice2 11110 115.226 0 0 0

Mice3 11120 115.227 0 0 0

Mice4 11130 115.228 0 0 0

Mice5 11140 115.229 0 0 0

Mice6 11150 115.23 0 0 0

Mice7 11160 115.231 0 0 0

Mice8 11170 115.232 0 0 0

Mice9 11180 115.233 0 0 0

Mice10 11190 115.234 0 0 0

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Reduced: 26mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 1620 9 0.00555556

Mice2 11110 115.226 0 0 0

Mice3 11120 115.227 0 0 0

Mice4 11130 115.228 0 0 0

Mice5 11140 115.229 0 0 0

Mice6 11150 115.23 0 0 0

Mice7 11160 115.231 0 0 0

Mice8 11170 115.232 0 0 0

Mice9 11180 115.233 0 0 0

Mice10 11190 115.234 0 0 0

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Reduced: 25mm above axis, 8 to 10ms

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Name Index Position [m] # Hits # Absorbed Efficiency

Mice1 11100 115.225 3286 22 0.00669507

Mice2 11110 115.226 0 0 0

Mice3 11120 115.227 0 0 0

Mice4 11130 115.228 0 0 0

Mice5 11140 115.229 0 0 0

Mice6 11150 115.23 0 0 0

Mice7 11160 115.231 0 0 0

Mice8 11170 115.232 0 0 0

Mice9 11180 115.233 0 0 0

Mice10 11190 115.234 0 0 0

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Reduced: 24mm above axis, 8 to 10ms

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Name Index Position [m] # Hits #Absorbed Efficiency

Mice1 11100 115.225 6039 38 0.00629243

Mice2 11110 115.226 0 0 0

Mice3 11120 115.227 0 0 0

Mice4 11130 115.228 0 0 0

Mice5 11140 115.229 0 0 0

Mice6 11150 115.23 0 0 0

Mice7 11160 115.231 0 0 0

Mice8 11170 115.232 0 0 0

Mice9 11180 115.233 0 0 0

Mice10 11190 115.234 0 0 0

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Circular-solid 6mm radius: 27mm above axis, 8 to 10ms

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Name Index Position [m] # Hits #

Absorbed

Efficien

cyMice1 11100 115.23 671 5 0.01Mice2 11110 115.23 820 0 0Mice3 11120 115.23 953 1 0Mice4 11130 115.23 1019 0 0Mice5 11140 115.23 1058 2 0Mice6 11150 115.23 1062 0 0Mice7 11160 115.23 1036 0 0Mice8 11170 115.23 982 0 0Mice9 11180 115.23 863 0 0

Mice10 11190 115.23 706 0 0

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SUMMARY of the SUMMARIESORBIT Results

Summary

Target Run Depth above axis (mm) LP end of spill MICE Collimator Hits MICE Collimator Absorber % Efficiency

Short Fat 6.1 27 454 1986 14 0.70493454

Long Thin 6.2 27 636 6027 5 0.08296001

Reduced 6.5 27 211 1044 6 0.57471264

Rotated 25deg 7.1 27 483 1835 5 0.27247956

Circular 6mm rad 8.1 27 1047 9170 8 0.087241

             

Long Thin 6.4 26 1083 10193 9 0.08829589

Reduced 6.6 26 352 1620 9 0.55555556

             

Reduced 6.7 25 700 3286 22 0.669507

             

Reduced 6.8 24 1347 6039 38 0.62924325

- in a sh.fat config. losses happen far from the tgt point-the long-thin (or cylindrical) config. suggest most of losses happenin S7-8, closer to the TGT prod point- more controllable with collimators/scrapers?

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G4Beamline StudiesM. Apollonio

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- is there a better shape for the target or orientation?- how many secondaries (pi) do we get at the Q1 bore (per impinging proton?)- what about materials?

ISIS p trajectory

Q1-

2-3

25o

MICE TGT

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10 mm

10 mm

XZ

25 deg

Q1-TGTaxis

25 deg

lostto Q1

secondariesproduction20<theta<30propagation toplane Aacos(Pz/Ptot)>20&& acos(Pz/Ptot)<30

rotation &propagation to plane B

A A

B

C

shift & align with Q1-TGT axis

LONG SLIM

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25 deg

25 deg

FAT SHORT

TILTED TGT10o / 25o

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25 deg

Cylinder: OD=6mm/ID=4.7 mm

Materials:Ti Be Al

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Tgt_long_slim_rot0: y:x Nprimaries=100M

A

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Tgt_long_slim: y:x rotation 25 deg + shift 4.226

B

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at Q1 plane in Q1 bore

C

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Tgt_tilt25_rot0: y:x Nprimaries=100M

A

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At Q1 plane Q1 bore C

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Tgt_short_fat_rot0: y:x

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Tgt_cyl_rot0: y:x

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config POT POT/mm2 Dx H BaseArea V Q1 Q1/(POT/mm2)rho(mm) (mm) (mm^2) (mm^3) g cm-3

cyl_Ti 2.50E+08 1.04E+07 6 4 10.92457 43.69827 7351 7.06E-04 4.54cyl_Be 1.00E+08 4.17E+06 6 4 10.92457 43.69827 1792 4.30E-04 1.85cyl_Al 1.00E+08 4.17E+06 6 4 10.92457 43.69827 2059 4.94E-04 2.70long_slim 5.00E+08 1.25E+08 1 4 10 40 79817 6.39E-04 4.54short_fat 5.00E+08 1.25E+07 10 4 10 40 8184 6.55E-04 4.54tilt_25 1.00E+08 4.81E+06 5.2 4 10 40 3092 6.43E-04 4.54tilt_10 1.00E+08 9.19E+06 2.72 4 10 40 6010 6.54E-04 4.54

expectedp n pi+ pi- mu+ mu- gam e+e- TOT A/rho pi+

cyl_Ti 3.68E-04 2.67E-04 2.04E-05 6.82E-06 6.24E-06 1.92E-06 3.43E-05 1.34E-06 7.06E-04 10.54 2.04E-05cyl_Be 2.38E-04 1.30E-04 1.15E-05 3.36E-06 7.44E-06 2.16E-06 3.82E-05 2.40E-07 4.30E-04 4.88 9.42E-06cyl_Al 2.74E-04 1.60E-04 1.51E-05 3.12E-06 8.16E-06 3.60E-06 2.93E-05 7.20E-07 4.94E-04 10.00 1.93E-05long_slim 3.34E-04 2.36E-04 2.05E-05 6.39E-06 5.57E-06 1.54E-06 3.25E-05 1.52E-06 6.39E-04short_fat 3.43E-04 2.44E-04 2.06E-05 5.36E-06 6.16E-06 1.60E-06 3.27E-05 1.36E-06 6.55E-04tilt_25 3.23E-04 2.49E-04 1.44E-05 5.62E-06 1.12E-05 1.66E-06 3.41E-05 3.95E-06 6.43E-04tilt_10 3.41E-04 2.46E-04 1.47E-05 4.90E-06 1.08E-05 1.96E-06 3.14E-05 3.37E-06 6.54E-04

Q1 breakdown (/POT/mm2)

cyl_Ti (6/4.6) 3.92E-04 2.85E-04 2.17E-05 7.27E-06 6.66E-06 2.05E-06 3.66E-05 1.43E-06 7.53E-04cyl_Ti (6/4.2) 4.85E-04 3.53E-04 2.69E-05 9.00E-06 8.24E-06 2.53E-06 4.52E-05 1.77E-06 9.31E-04cyl_Ti (6/4.0) 5.29E-04 3.84E-04 2.93E-05 9.80E-06 8.97E-06 2.76E-06 4.93E-05 1.93E-06 1.01E-03

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CONCLUSIONS

- neither the shape nor the orientation of a target seem to alter significantly the production of secondaries to Q1- the overall material volume intercepted by the beam is the main parameter (reasonable) - material other than Ti (lower A/rho) generate less secondaries (in particular pions)-a good balance should be found between weight / mechanical stiffness / andpion production-a hollow cylinder is a good solution, certainly does not worsen the performances ofthe present configuration