Study of SHMS resolution

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 2 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 2 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. The resolution can also depend on the target quantities which is shown in the plots with links below the table.

	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 20 mil Al exit window, vacuum pipe , Kevlar entrance window	0.94	0.94	.077	.15
6	wire chamber smearing, multiple scattering in all materials with 20 mil Al exit window,helium bag, Kevlar entrance window	0.86	0.92	.113	.22
7	wire chamber smearing, multiple scattering in all materials with 20 mil Al exit window,helium bag, 20 mil Alum entrance window	0.96	1.05	.113	.22
8	wire chamber smearing, multiple scattering in all materials with 12 mil Al exit window,helium bag, 12 mil Alum entrance window	0.96	1.03	.097	.21
9	wire chamber smearing, multiple scattering in all materials with 20 mil Al exit window,air, 20 mil Alum entrance window	1.1	1.2	.137	.25

• 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 [xptar],[yptar], [ytar] and [delta] versus the thrown delta, xptar and yptar comparing sets 6 and 7 listed in the above table.
• Plots of [xptar],[yptar], [ytar] and [delta] versus the thrown delta, xptar and yptar comparing sets 7 and 8 listed in the above table.
• Plots of [xptar],[yptar], [ytar] and [delta] versus the thrown delta, xptar and yptar comparing sets 7 and 9 listed in the above table.

Comparing resolutions with Cerenkov

• Run single arm MC with 20cm LH2 target at 20deg
• Include wire chamber resolution with 20mil aluminum entrance and exit windows for the SHMS.
• Table with the resolution for xptar, yptar, ytar and delta for all events. The resolution can also depend on the target quantities which is shown in the plots with links below the table.

	Electron Momemtum	Xptar (mr)	Yptar (mr)	Delta %	Ytar (cm)
1	2 GeV	1.6	1.4	0.20	.33
2	6 GeV	0.66	0.69	0.084	.21

• Plots of [xptar],[yptar], [ytar] and [delta] versus the thrown delta, xptar and yptar comparing sets 1 and 2 listed in the above table.