Difference between revisions of "Study of SHMS resolution"
From HallCWiki
Jump to navigationJump to search| Line 29: | Line 29: | ||
= Comparing resolutions with vaccuum pipe versus helium bag = | = Comparing resolutions with vaccuum pipe versus helium bag = | ||
* Monte Carlo run for 2 GeV electrons for 20cm LH2 target with spectrometer at 20 degs. | * Monte Carlo run for 2 GeV electrons for 20cm LH2 target with spectrometer at 20 degs. | ||
| − | * Table with the | + | * Table with the resolution for xptar, yptar, ytar and delta for all events |
{|border="1" align="center" | {|border="1" align="center" | ||
!Single arm Monte Carlo Flags !! Xptar (mr) !! Yptar (mr) !! Delta % !! Ytar (cm) | !Single arm Monte Carlo Flags !! Xptar (mr) !! Yptar (mr) !! Delta % !! Ytar (cm) | ||
| Line 41: | Line 41: | ||
! wire chamber smearing, multiple scattering in all materials with helium bag || 1.04 || 0.96 || .092 || .14 | ! wire chamber smearing, multiple scattering in all materials with helium bag || 1.04 || 0.96 || .092 || .14 | ||
|} | |} | ||
| − | * Plots of [[https://hallcweb.jlab.org/wiki/images/3/3f/Comp_resol_xptar.gif xptar]] , [[https://hallcweb.jlab.org/wiki/images/3/30/Comp_resol_yptar.gif yptar]], [[https://hallcweb.jlab.org/wiki/images/6/6a/Comp_resol_ytar.gif ytar]] and [[https://hallcweb.jlab.org/wiki/images/f/fe/Comp_resol_delta.gif delta]] resolutions versus the thrown delta, xptar and yptar. | + | * Plots of [[https://hallcweb.jlab.org/wiki/images/3/3f/Comp_resol_xptar.gif xptar]] , [[https://hallcweb.jlab.org/wiki/images/3/30/Comp_resol_yptar.gif yptar]], [[https://hallcweb.jlab.org/wiki/images/6/6a/Comp_resol_ytar.gif ytar]] and [[https://hallcweb.jlab.org/wiki/images/f/fe/Comp_resol_delta.gif delta]] resolutions versus the thrown delta, xptar and yptar |
| + | comparing the four different sets of MC flags listed in the above table. | ||
Revision as of 11:57, 28 February 2012
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) followed by 15 cm air (X0=30420cm)
- Spectrometer entrance window 15 mil Kevlar (X0=74.6cm) and 5 mil Mylar (X0=28.7cm)
- Spectrometer exit window spectrometer exit window, 15 mil Kevlar, 5 mil Mylar (use 20 mil,X0=53.3)
- 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 17 micron mylar and 3 micron aluminum. Filled with helium ( Radlen = 754560 cm).
- Drift through air until drift chamber 1
- Chamber 1 entrance foil, 1 mil of Mylar
- Scattering in drift chamber, for each plane
- Effective cathode plane, Be/Cu with Rad Len = 28.7cm , 0.0005 in
- Drift through Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm
- Effective wire plane, 25 micron W+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
- Scattering in drift chamber, for each plane
- Effective cathode plane, Be/Cu with Rad Len = 28.7cm , 0.0005 in
- Drift through Chamber gas, 50/50 ethane/argon with Rad Len = 16700.0cm
- Effective wire plane, 25 micron W+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 vaccuum 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) |
|---|---|---|---|---|
| no wire chamber smearing, no multiple scattering in material | 0.08 | 0.01 | .014 | .002 |
| wire chamber smearing, no multiple scattering in material | 0.36 | 0.26 | .038 | .084 |
| wire chamber smearing, multiple scattering in all materials with vacuum pipe | 1.00 | 0.94 | .072 | .12 |
| wire chamber smearing, multiple scattering in all materials with helium bag | 1.04 | 0.96 | .092 | .14 |
comparing the four different sets of MC flags listed in the above table.
