Study of SHMS resolution
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Revision as of 11:12, 8 March 2012 by Jones (talk | contribs) (→Comparing resolutions with vacuum pipe versus helium bag)
Using the following setup for SHMS single arm MC
- 2 GeV , 20 deg scattered electrons
- Reconstruction of tracks in the focal plane assumed 200 microns resolution.
- LH2 target with 20cm length. Assume beer can with radius of 3.37cm and wall thickness in 0.005in Al.
- 16 mil Al scattering chamber window (X0=8.89cm, frac rad len = 0.46%) followed by 15 cm air (X0=30420cm, frac rad len =0.05%)
- Two options for for spectrometer entrance window
- 15 mil Kevlar, 5 mil Mylar (use 20 mil,X0=53.3, Frac Rad len = 0.095%)
- 0.02inches of Aluminum (Frac Rad len = 0.57%)
- Two options for spectrometer exit window,
- 15 mil Kevlar, 5 mil Mylar (use 20 mil,X0=53.3, Frac Rad len = 0.095%)
- 0.02inches of Aluminum (Frac Rad len = 0.57%)
- Two options in Hut when AR/Neon Cerenkov is removed
- Vacuum pipe so the the spectrometer exit window is moved to location of Cerenkov exit window
- Helium bag. The spectrometer exit window is located in front of Cerenkov entrance, but the Cerenkov is replaced by a helium bag. Assume the entrance and exit of helium bag is aluminized mylar.
- Each window is 0.010 inches mylar (Frac Rad len = 0.089%) and 3x10-4 cm aluminum (Frac Rad len = 0.03%).
- Filled with helium ( Radlen = 754560 cm, Frac Rad len = 0.03%).
- Drift through air until drift chamber 1 (Frac Rad len = 0.06%).
- Chamber 1 entrance foil, 1 mil of Mylar (Frac Rad len = 0.009%) ( ignore 1000 Angstrom aluminum)
- Drift through 1/8 inch of Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm (Frac Rad len = 0.002%)
- Scattering in drift chamber, for each plane
- Effective cathode plane, 1 mil Kapton ( Radlen = 28.6 cm, Frac Rad len = 0.009%).
- Drift through 1/8 inch of Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm (Frac Rad len = 0.002%)
- Effective wire plane, 25 micron W + 100 micron Be/Cu
- Fill hit position for plane
- Drift through Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm
- Chamber 1 exit foil, 1 mil of Mylar
- Drift through air until drift chamber 2
- Chamber 1 entrance foil, 1 mil of Mylar (Frac Rad len = 0.009%) ( ignore 1000 Angstrom aluminum)
- Drift through 1/8 inch of Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm (Frac Rad len = 0.002%)
- Scattering in drift chamber, for each plane
- Effective cathode plane, 1 mil Kapton ( Radlen = cm, Frac Rad len = 0.0%).
- Drift through 1/8 inch of Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm (Frac Rad len = 0.002%)
- Effective wire plane, 25 micron W + 100 micron Be/Cu
- Fill hit position for plane
- Drift through Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm
- Chamber 1 exit foil, 1 mil of Mylar
Comparing resolutions with vacuum pipe versus helium bag
- Monte Carlo run for 2 GeV electrons for 20cm LH2 target with spectrometer at 20 degs.
- Table with the resolution for xptar, yptar, ytar and delta for all events
| Single arm Monte Carlo Flags | Xptar (mr) | Yptar (mr) | Delta % | Ytar (cm) | |
|---|---|---|---|---|---|
| 1 | no wire chamber smearing, no multiple scattering in material | 0.17 | 0.09 | .031 | .037 |
| 2 | wire chamber smearing, no multiple scattering in material | 0.30 | 0.35 | .041 | .010 |
| 3 | wire chamber smearing, multiple scattering in all materials with Kevlar exit window, vacuum pipe, Kevlar entrance window | 0.86 | 0.87 | .058 | .15 |
| 4 | wire chamber smearing, multiple scattering in all materials with Kevlar exit window,helium bag, Kevlar entrance window | 0.86 | 0.89 | .077 | .15 |
| 5 | wire chamber smearing, multiple scattering in all materials with Al exit window, vacuum pipe , Kevlar entrance window | 0.94 | 0.94 | .077 | .15 |
| 6 | wire chamber smearing, multiple scattering in all materials with Al exit window,helium bag, Kevlar entrance window | 0.86 | 0.92 | .113 | .18 |
| 7 | wire chamber smearing, multiple scattering in all materials with Al exit window,helium bag, Alum entrance window | 0.96 | 0.92 | .113 | .18 |
- Plots of [xptar] , [yptar], [ytar] and [delta] resolutions versus the thrown delta, xptar and yptar comparing the sets 1,2,3 and 4 listed in the above table.
- Plots of [xptar] , [yptar], [ytar] and [delta] resolutions versus the thrown delta, xptar and yptar comparing the sets 1,2,5 and 6 listed in the above table.
- Plots of [xptar],[yptar], [ytar] and [delta] versus the thrown delta, xptar and yptar comparing sets 3,4,5 and 6 listed in the above table.
- Plots of [[Image:Comp_resol4_xptar.gif ] xptar],File:Comp resol4 yptar.gif yptar, File:Comp resol4 ytar.gif ytar and File:Comp resol4 delta.gif delta versus the thrown delta, xptar and yptar comparing sets 6 and 7 listed in the above table.
