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| | *[[Minutes SHMS MC 2 | Minutes for Sept 2 2011 meeting]] | | *[[Minutes SHMS MC 2 | Minutes for Sept 2 2011 meeting]] |
| | *[[Minutes SHMS MC 1 | Minutes for June 8 2011 meeting]] | | *[[Minutes SHMS MC 1 | Minutes for June 8 2011 meeting]] |
| − | | + | [[Category:SHMSinfo]] |
| | ==SHMS Characteristics== | | ==SHMS Characteristics== |
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| | ===Drawings of magnets=== | | ===Drawings of magnets=== |
| − | **[[https://hallcweb.jlab.org/wiki/images/d/d2/Shms_q3_dipole_sideview.jpg Side view drawing ]] of the SHMS Q3 and Dipole with distances. The far left cross hair in the drawing is the x_hut=y_hut=z_hut=0 point from which the detector positions are measured in the hut. The distance from the dipole center to the "zero" point projected perpendicular to the mechanical center axis of the dipole is 3.65m as shown on [https://hallcweb.jlab.org/wiki/images/d/d2/Q3-dipole.pdf an annotated] drawing with the calculation. [[https://hallcweb.jlab.org/wiki/images/5/51/Shms_detector_distances.jpg Plot]] of detector distances from the "zero" point. (From Mike Fowler on Sept 12th, 2011)
| + | *[[Drawings_of_SHMS_magnets | Drawings of SHMS magnets ]] |
| − | **[[https://hallcweb.jlab.org/wiki/images/a/af/Dipole_entrance.jpg Drawing ]] with measurements of the dipole entrance flange. [[https://hallcweb.jlab.org/wiki/images/c/c8/Dipole_entrance_3d.jpg 3d picture ]] of the dipole entrance.
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| − | *[[https://hallcweb.jlab.org/wiki/images/9/9c/Shms_magnet_field_summary.pdf Summary table ]] of the SHMS magnets field properties. From Steve Lassiter file magnet_summary.doc on Sept 9th 2011.
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| − | *Horizontal bender magnet dimensions (Mike Fowler on Sept 12th, 2011): [[https://hallcweb.jlab.org/wiki/images/a/a0/Bender_Dimensions_topview.jpg Top view]] , [[https://hallcweb.jlab.org/wiki/images/c/c7/Bender_Dimensions_3d.jpg 3-D view]], a few more views of the H bender from 2010, [[Media:Hb_topview.png|top view]], [[Media:Hb_topview2.png| top view at the smallest spectrometer angle]], [[Media:Hb_frontface.png| front face view]], [[Media:Hb_sideview1.png|side view]], [[Media:Hb_sidesectional.png| side sectional view]], [[Media:Hb_topsectional.png| top sectional view]], [[Media:ScreenShot112.jpg| view of aperture]]
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| − | *Dipole apertures used in the MC model: The following figures describe how to calculate the parameters required to describe the dipole apertures in the MC. The dipole effective length is divided into 8 equal segments and the aperture center and inclinations are calculated at each of these segments. The inclinations angles are shown in [[Media:angles.png| angles]], and the drift distances and offsets of the center of the aperture with respect to the central trajectory are shown in table of offsets [[Media:shms_geometry_2.png| (20 cm drop)]] and [[Media:shms_geometry_2.6.png| (26 cm drop)]]
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| − | [[Category:SHMSinfo]]
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| | | | |
| | === Study of the SHMS resolution === | | === Study of the SHMS resolution === |
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| | == SNAKE == | | == SNAKE == |
| − | === Field maps of magnets ===
| + | Moved Snake section [[SNAKE Transport code | here.]] |
| − | *The Horizontal Bender
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| − | **The integral field needed for 3 deg bend is 1.9211 Tm.
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| − | **From map file, ''MSU_Bender.map'', the maximum integral field along a straight path is 1.92929 Tm with B_max=2.4768 T giving L_eff= 0.7789m. So need a factor of 0.996 to scale map toget field for 3deg bend.
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| − | *Dipole
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| − | **The integral field needed for 18.4 deg bend is 11.783 Tm for integration along the path of the particle, L_arc, which is incident perpendicular to the field. The difference between the L_arc and the straight line L_eff is L_arc/L_eff = theta/sin(theta)=1.017 for theta=18.4 deg. So need integral field along a straight path of 11.586 Tm.
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| − | **From map file, ''shmsD2008.map'', B_max=4.7907 and Int(Bdl) = -13.67883 so L_eff=2.855. So need a factor of 0.8478 to scale map to get field for 18.4 deg bend.
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| − | * Quadrupoles
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| − | **From map file, ''Q1_coldiron.map'',Max Bz/r= 10.791 and Int(Bz/r*dl) = 19.9049 for L_eff= 1.844 at r=20cm
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| − | **From map file,''Q23nc6.map'', Max Bz/r=14.41324 and Int(Bz/r*dl) = 23.04041 for L_eff=1.5985 at r=31cm
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| − | **Determine the scale factors for the quads to given desired 1st order optics.
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| − | | |
| − | === Determine the magnet setting for 11 GeV/c ===
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| − | *Fix the map scale factor for the HB and Dipole fields at 0.996 and 0.8478 .
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| − | *Determine the scale factors for the quads, by modifying them so that (xfp|xptar)=0, (yfp|ytar)=1.634 and (yfp|yptar)=0 in 1st order matrix. Found scale factors are -0.792092,0.845324,-0.526535 .
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| − | * 1st order Matrix from target to focal plane has D/M = -1.09:
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| − | {|border="1" align="center"
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| − | ! !!xtar !! xptar !! ytar !! yptar!! delta
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| − | |-
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| − | !xfp || -1.501|| -0.002 ||-0.024 ||-0.054 || 1.634
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| − | |-
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| − | !xpfp|| -0.049 ||-0.663 || 0.001|| 0.002 || 0.310
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| − | |-
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| − | !yfp || -0.004 ||-0.002 ||-1.634|| -0.001 ||-0.025
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| − | |-
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| − | !ypfp || 0.000 || 0.003 ||-0.277|| -0.623 || 0.020
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| − | |}
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| − | *With new scale factors:
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| − | ** Q1 Max B = -1.7093 Int(Bdl) = 3.153304 Int(B/rdl) = 15.76652 at r=0.20m L_eff= 1.844
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| − | ** Q2 Max B = 3.778 Int(Bdl) = 6.03996 Int(B/rdl) = 19.4736 at r=0.31m L_eff=1.5985
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| − | ** Q3 Max B = -2.3536 Int(Bdl) = 3.76275 Int(B/rdl) = 12.1316 at r=0.31m L_eff=1.5985
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| − | ** Overall path length = 18.10325m for central track
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| − | *For comparison to COSY, Dave Gaskell optimized for (xfp|xptar)=0, (yfp|yptar)=0 and D/M=-1.09
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| − | ** Q1=-2.128585 T at 25cm which at 20cm is q1 = -1.7028 using L_eff = 1.879m.
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| − | ** Q2= 4.342608 T at 35cm which at 31cm is q2 = 3.8463 using L_eff=1.64m.
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| − | ** Q3=-2.805149 T at 35cm which at 31cm is q3 = -2.484 using L_eff=1.64m.
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| − | === Study of changing the vertical offset of dipole ===
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| − | *Ran SNAKE with set of random trajectories for point target with -0.060 < xptar < 0.060, -0.040 < yptar < 0.040 and 8.8 < momentum < 13.42 GeV/c.
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| − | *Input deck to SNAKE has 38 endplanes or apertures. An endplane is a position within SHMS where the the positions and angles are recorded. If the track goes outside the SHMS good volume then a flag is set to indicate a failed track and the positions and angles at the location between the endplanes is recorded.
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| − | *Compared an vertical offset of 20cm, 26cm and 29cm. For each offset the distance between the centerof the dipole and the focal plane center is recalculated.
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| − | *[https://hallcweb.jlab.org/wiki/images/3/3b/Comp_endpl_20-29.gif 1D Plot] of fraction of total tracks which failed for each endplane number for offset of 20cm (red), 26cm (black) and 29cm (green) offsets.. Apertures (or Endplanes) numbers 3-7 are HB, 8-13 are Q1, 14-18 are Q2, 19-24 are Q3, 25 is dipole entrance, 26-35 are dipole.
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| − | *2D plot of number tracks which failed for each endplane number versus xptar and yptar for offset of [https://hallcweb.jlab.org/wiki/images/c/cb/20cm_endpl_xy.gif 20cm] , [https://hallcweb.jlab.org/wiki/images/0/09/26cm_endpl_xy.gif 26cm] and [https://hallcweb.jlab.org/wiki/images/2/21/29cm_endpl_xy.gif 29cm]. The HB vertical size limits the xptar acceptance to about +/-47-50mr. The Q1 exit limits the horizontal acceptance. For the 20cm offset in the dipole, the dipole entrance (#25) limits the negative xptar acceptance with a delta dependence.
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| − | *1D Plots of target xp,yp, delta and ytar with for offset of [https://hallcweb.jlab.org/wiki/images/7/7b/20cm_tar.gif 20cm], [https://hallcweb.jlab.org/wiki/images/9/9c/26cm_tar.gif 26cm] and [https://hallcweb.jlab.org/wiki/images/b/b7/29cm_fp.gif 29cm]. The black line is all tracks. The blue line is failed tracks. The red line is passed tracks.
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| − | *[https://hallcweb.jlab.org/wiki/images/2/29/Comp_delta_20-29.gif Plot] comparing the solid angle has a function of delta for 20 (red), 26cm (black) and 29cm (green) offsets. The solid angle is calculated by the ratio of passed tracks to total tracks multiplied by 0.12*0.08*1000 (the thrown solid angle in msr at each delta).
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| − | *2D Plots of target xp/delta, yp/delta and xp/yp for offset of [https://hallcweb.jlab.org/wiki/images/8/8f/20cm_2dtar.gif 20cm], [https://hallcweb.jlab.org/wiki/images/c/c4/26cm_2dtar.gif 26cm] and [https://hallcweb.jlab.org/wiki/images/1/19/29cm_2dtar.gif 29cm].
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| − | *2D Plots of focal plane x/y, xp/yp, yp/y and xp/x for offset of [https://hallcweb.jlab.org/wiki/images/e/e9/20cm_fp.gif 20cm], [https://hallcweb.jlab.org/wiki/images/c/c0/26cm_fp.gif 26cm] and [https://hallcweb.jlab.org/wiki/images/b/b7/29cm_fp.gif 29cm].
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| − | === Study comparing SHMS tuned to D/M = -1.1 to D = -0.8 ===
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| − | *Ran SNAKE with set of random trajectories for point target with -0.060 < xptar < 0.060, -0.040 < yptar < 0.040 and 8.8 < momentum < 13.42 GeV/c.
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| − | *Dave Gaskell fitted tune in COSY for D/M=-0.8 . Scaled the magnets fields in SNAKE.
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| − | *[https://hallcweb.jlab.org/wiki/images/a/a4/Comp_delta_20-26_dm.gif Plot] comparing the solid angle has a function of delta for 20 (red) and 26cm (black) offsets at D/M=-1.1 and 26cm offset with D/M=-0.08 (green). The solid angle is calculated by the ratio of passed tracks to total tracks multiplied by 0.12*0.08*1000 (the thrown solid angle in msr at each delta).
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| − | *[https://hallcweb.jlab.org/wiki/images/f/fc/Comp_endpl_20-26_dm.gif 1D Plot] of fraction of total tracks which failed for each endplane number for offset of 20cm (red) and 26cm (black) at D/M=-1.1 and 26cm offset with D/M=-0.8 (green).
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| − | *2D Plots of target xp/delta, yp/delta and xp/yp for offset of [https://hallcweb.jlab.org/wiki/images/c/c4/26cm_2dtar.gif 26cm] with D/M=-1.1 and [https://hallcweb.jlab.org/wiki/images/d/d5/26cm_dm08_2dtar.gif 26cm] with D/M=-0.8.
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| − | | |
| − | === Study of changing the vertical opening of the HB ===
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| − | *[https://hallcweb.jlab.org/wiki/images/0/0e/HB_Vacuum_Bore_Change.jpg Drawing] of the proposed change by Mike Fowler on Sept 28th.
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| − | *[https://hallcweb.jlab.org/wiki/images/3/3b/Comp_delta_26-HB.gif Plot] comparing the solid angle has a function of delta for HB vertical opening of 20.75cm(red) and 23cm (black) with dipole offset = 26cm. The solid angle is calculated by the ratio of passed tracks to total tracks multiplied by 0.12*0.08*1000 (the thrown solid angle in msr at each delta). With the increased HB acceptance, the xptar acceptance grows about 10% in negative delta region. Makes no difference in positive delta region.
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| − | | |
| − | ===SNAKE versus COSY comparison ===
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| − | * Ran SNAKE for xptar = +/- 80mr , yptar = +/- 80mr , -22 < delta < 33 and 20cm target at 20deg. Ran mc_shms_single for xptar = +/- 80mr , yptar = +/- 80mr , -22 < delta < 22 and 20cm target at 20deg.
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| − | *[https://hallcweb.jlab.org/wiki/images/7/74/Delta_cosy_snake.gif Plot] comparing solid angle acceptance versus delta for SNAKE (blue) and COSY (red).
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| − | *[https://hallcweb.jlab.org/wiki/images/4/4c/Comp_snake_cosy.gif Plots] comparing x (vertical) and y (horizontal) positions at various locations from dipole optical entrance to the focal plane for SNAKE (blue) and COSY (red).
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| − | | |
| − | ===Collimator study ===
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| − | * Run SNAKE with target of length +/-10cm at 20deg. Use a 26cm offset in the dipole with 23cm opening in HB.
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| − | *[https://hallcweb.jlab.org/wiki/images/8/8b/Comp_q1_failed_dipole.gif Plot] of the vertical position versus the horizontal position at Q1 entrance. The red boxes are events which are accepted up through aperture #11 ( as defined in [https://hallcweb.jlab.org/wiki/images/7/75/Shms_geometry_2.6.png plot] of apertures in SIMC). The green boxs are events which fail at aperture #12. The blue boxes are those events which fail in aperture #13 and after.
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| − | *Study putting a cut at the vertical position at the Q1 entrance. Table of solid angle and fractional loss is percentage of events which have made it through Q1 but fail either in aperture #12 and after, or in aperture #13 and after:
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| − | {|border="1" align="center"
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| − | ! Cut !! Solid angle !! Frac loss after #13 !! Frac loss after #12
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| − | |-
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| − | ! none || 3.75mr || 3.6% || 4.7%
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| − | |-
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| − | ! <+7cm || 3.10|| 0.0% || 1.4%
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| − | |-
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| − | ! <+9cm || 3.38|| 0.2% || 1.5%
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| − | |-
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| − | ! <+11cm ||3.60 || 1.5% || 2.6%
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| − | |-
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| − | ! <+13cm ||3.75 || 3.6% || 4.7%
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| − | |} | |
| − | *[https://hallcweb.jlab.org/wiki/images/3/3b/Comp_delta_coll.gif Plot] of solid acceptance versus delta for cuts in the vertical acceptance at the entrance of Q1 for events with vertical position at Q1 less than 7 (red) , 9 (green), 11 (purple) and 13cm (cyan).
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| − | *Phase space of beam through SHMS. 2d histograms of the relative vertical ( y-axis) vs horizontal ( x-axis) positions at different locations in the [https://hallcweb.jlab.org/wiki/images/e/e5/Xy_hb.gif Horizontal Bender],[https://hallcweb.jlab.org/wiki/images/7/7a/Xy_q1.gif Q1], [https://hallcweb.jlab.org/wiki/images/1/10/Xy_q2.gif Q2], [https://hallcweb.jlab.org/wiki/images/e/e7/Xy_q3.gif Q3], [https://hallcweb.jlab.org/wiki/images/1/1c/Xy_dent.gif Dipole entrance],[https://hallcweb.jlab.org/wiki/images/a/a6/Xy_dexit.gif Dipole exit]. The coordinates are in the coordinate system relative to the center of that magnet element. The vertical axis has positive direction is physical down. The horizontal axis has positive direction is away from beam line. The blue squares are events which make it to the focal plane. The colored squares are events which are rejected at the aperture. The critical aperatures are the HB entrance (horizontal), HB optical and physical exit (vertical), Q1 optical and physical exit (vertical and horizontal), dipole entrance (negative vertical), dipole middle and before (positive vertical), dipole exit (negative vertical).
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| − | *Investigation of sieve slit placement. Run snake for a point target with -0.20 < delta < 0.22, abs(yptar) < 0.40 and abs(xptar) < 0.60 with sieve slit in front of Q1. [https://hallcweb.jlab.org/wiki/images/1/1a/Sieve_xytar.gif 2D Plots] of xptar versus delta, yptar versus delta, xptar versus yptar and x versus y at sieve position. One sees the correlation between yptar and delta to get through a fixed horizontal hole position at the Q1 sieve. A rough estimate has del(yptar)/del(delta) = 0.02 so knowledge of delta to the 5% level allows one to predict yptar to the 1mr level.
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| | == COSY == | | == COSY == |
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| | * [[Media:collimator2_0.08.png |Plot1]], [[Media:collimator2_0.12.png |Plot2]] of vertical position vs horizontal position at Q1 entrance for events with vertical position at Q1 less than 7 (green) , 11 (magenta), 13cm (blue) and no cut (red). Plot1 is for D/M=0.08 and Plot2 is for D/M=0.12, cut on delta -10<delta<22 | | * [[Media:collimator2_0.08.png |Plot1]], [[Media:collimator2_0.12.png |Plot2]] of vertical position vs horizontal position at Q1 entrance for events with vertical position at Q1 less than 7 (green) , 11 (magenta), 13cm (blue) and no cut (red). Plot1 is for D/M=0.08 and Plot2 is for D/M=0.12, cut on delta -10<delta<22 |
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| | + | __FORCETOC__ |
| | + | [[Category:SHMSinfo]] |
| | == SLITS and COLLIMATORS == | | == SLITS and COLLIMATORS == |
| − | *[[http://www.jlab.org/Hall-C/upgrade/SHMS_OPTICS/shms_collimator.pdf Sieve slit placement & design (T. Horn)]]
| + | Moved to [[Collimators and Slits for SHMS | Collimators and Slits for SHMS]] |
| − | *[[ Media:sieve1.png |sieve1]], sieve slit plot to compare with Tanja's study above.
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| − | *[[ Media:coll1.png |Collimator1]], [[ Media:coll2.png |Collimator2]] and [[Media:coll3.png|Collimator 3]] using the validated mc_shms for 20 cm target at 20 degrees, three collimators are shown, the first is an octagon of 28cm x 14 cm the second is an octagon of 28cm x 18 cm. The first one reduced the acceptance by about 12%, the second one reduces it by less than 1% and the third is an octagon of 23 cm x13 cm which reduced the acceptance by about 24%. In each figure the top left panel shows the x vs y at Q1 entrance, for those events that made it up to the dipole entrance without any collimator on the way. The top right panel shows the x vs y at the collimator for events that make it past the collimator. The bottom left is the overlap of the top two panels and bottom right is overlap of the top right and x vs y at the Q1 entrance for those event that make it to the focal plane without any collimator (including colorimeter feducial cuts).
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| − | *[[ Media:coll_delta.png |New Collimator1]], The collimators cannot be placed flush with the Q1 entrance, as in the above figures. The space for the collimator box is at 80 cm from the HB mid-point or about 33 cm from the Q1 entrance. Three sizes of collimators are shown in the figure, 25cm x 17cm, 20cm x 17cm and 18cm x 17cm. These were simulated for a 20 cm target at 20 degree with a -12% to +15% delta cut. The variation of the acceptance with delta is also shown in the figure. There is 8.5% loss of events in the dipole for the 25x17 collimator, 4.6% loss for the 20x17 collimator and a 2.2% loss of events in the dipole with the 18x17 collimator. from this we conclude that the Large collimator will be 25cm x17cm and the small collimator will be 17 cm x17cm octagonal holes.
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| − | *[[ Media:Coll_design.png |Large Collimator Design]], [[ Media:Coll_design2.png |Small Collimator Design]], [[ Media:Sieve_design1.png |Sieve Slit Design]], [[ Media:Sieve_Design2.png |second Sieve Slit Design]] draft designs of the collimators and sieve slit
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| − | *[[ Media:sieve_d1.png |sieve1_a]], [[ Media:sieve_d2.png |sieve1_b]] sieve slit plots for the first sieve slit shown in the draft design
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| − | *[[ Media:sieve2_d1.png |sieve2_a]], [[ Media:sieve2_d2.png |sieve2_b]] sieve slit plots for the first sieve slit shown in the draft design
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| − | *[[ Media:sieve_d1_comp.png |sieve1_a compare]], [[ Media:sieve_d2_comp.png |sieve1_b compare]] sieve slit plots for the first sieve slit compared with and without the HB. Red shows the events with HB (same as the 2 plots above) and the blue are events without HB. This demonstrates the influence of the HB on the y, y' and delta (and no effect on the x, x'). It also shows us that just one sieve slit in front of Q1 will not be sufficient for optimizing the reconstruction matrix elements.
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| − | *[[ Media:sieve_r2.png |sieve_r2]], Sieve slot plots after adding a tally of materials in a GEM chamber to simulate the effect on the resolution and its possible use along with the sieve slits as a second set of active collimators.
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| | == Detector Positions == | | == Detector Positions == |
| | Moved to [https://hallcweb.jlab.org/wiki/index.php/Detector_Locations_in_SHMS Detector_Locations_in_SHMS] location | | Moved to [https://hallcweb.jlab.org/wiki/index.php/Detector_Locations_in_SHMS Detector_Locations_in_SHMS] location |
