1 gaskelld 1.1 SIMC 2001 release:
 2              
 3              IMPORTANT NOTE:  This is the first full release in over 18 months.  Many
 4              changes were made and I've tried to check them carefully, but I did not
 5              verify that every change made was perfect for all running conditions.
 6              If you have a running SIMC, you should start by running the new SIMC in
 7              identical kinematics, and making sure that nothing strange is happening.
 8              If you have ANY problem getting the new version to run, let me know and
 9              send me your input file, and I'll see if I can figure out the problem
10              (many problems might just be caused by overlooking changes to the input files).
11              
12              
13              New release of SIMC.  Major changes:
14              -----------------------------------
15              1. Preliminary version of Hall A spectrometers (At the moment, ntuple still
16                 uses hms/sos variable names, coordinate systems, units, etc...).  HRSR
17                 variables come out in the HMS variables (e.g. hsdelta), HRSL --> SOS.
18                 Target can geometry is still the Hall C version, but you can use either
19                 Beer can or tuna can targets and give it the length, so it should be an
20                 OK approximation.  Kaon decay is handled properly if doing_decay=1 (i.e.
21                 simulate decay event by event, though you have to reject just events that
22 gaskelld 1.1    decay before the aerogel, not all events).  For doing_decay=0 (apply the
23                 survival probability as a weight), the pathlength is calculated for the
24                 entire trip through the spectrometer, and the projected back to the approx.
25                 location of the aerogel.  This needs to be checked.
26              2. Pion and Kaon electroproduction are now done consistantly, event generation
27                 limits have been simplified, and variable defns. made more consistent.
28              3. The routines that are shared by the different spectrometer models (project,
29                 transp, musc, etc...) are now in the 'shared' directory.  They used to
30                 be in the SOS.  This was done so that the single arm monte carlos would
31                 use the same code and directory structures as the coincidence MC (SIMC).
32              4. Many little but fixes, largely in spectrometer models, offsets, etc...
33              
34              
35              EXTERNAL CHANGES (e.g. things that must be modified in the input files):
36              -----------------------------------------------------------------------
37              These are the changes relative to the latest release (120899).
38              1. Replaced doing_piplus flag with which_pion (see comments in .inp files).
39              2. "hard_cuts" flag.  Applies 'SPedge' and 'cuts.Em.max' cuts to events
40                 before determining success and before ntuple.
41              3. "hms_e_flag", which determined which arm had the electron, is now replaced
42                 with "electron_arm" and "hadron_arm" flag.  1=hms,2=sos,3=hrsr,4=hrsl.
43 gaskelld 1.1 4. "targ.mrec_amu"  is the mass of the recoil (A-1) system, for all physics
44                 processes (it used to be the A-2 mass for pion/kaon generation).
45              
46              
47              
48              ADDITIONAL FEATURES/CHANGES:
49              ----------------------------
50              1. Multiple scattering of incoming beam (record scattering of initial
51                 electron, and apply as shifts to both outgoing particles when passed
52                 to the spectrometers).
53              2. Updated documentation on pion event generation from Dave Gaskell.
54              3. Kaon/Pion electroproduction now use a spectral function rather than
55                 just a momentum distribution.
56              4. Updated HMS optics model (includes small Q2 rotation, and Q3 momentum
57                 offset which should be roughly correct for field100 values (post-1999).
58              5. 'expert' feature: sieve slits in the spectrometer.  You have to go into
59                 mc_***.f and set "use_sieve" to .true. and open the apertures.  It 
60                 puts in a 'mock' sieve slit by forcing the angles of events to go through
61                 the nearest 'hole'.  There are no missing/large/smaller holes, but the
62                 spacing should match the sieve slit for each spectrometer.
63              6. Fixed coordinate system with target/spectrometer offsets.  For target
64 gaskelld 1.1    offsets, x=right, y=up (as with most raster/BPM info), z=downstream.
65                 For spectrometer offsets, we use the spec. coord system (x=down, y=left).
66                 The spectrometer offsets are meant to give the actual value of the
67                 spectrometer, relative to the nominal kinematics (i.e. a positive x offset
68                 means that the spectrometer is too low, and so applying it will raise
69                 particles w.r.t. the spectrometer, and shift the x distribution to negative
70                 values).
71              
72              
73              MINOR OR PURELY INTERNAL UPDATES:
74              ---------------------------------
75              1. Checking drift distances thru spectrometer against MEs to avoid errors in
76                 total drift length.
77              2. Sanity check for multiple scattering (MeV vs. GeV problems)
78              3. Decdist array replaced with permanent variables.
79              4. Em/Pm added to default histos (.gen file - showing generated Em/Pm)
80              5. Bug fix - HMS aperture checks, drift lengths, collimator offsets, etc...
81              
82              
83              THINGS TO COME:
84              ---------------
85 gaskelld 1.1 Mostly cosmetic changes and more sanity checks of input variables.
86              Note however, that physics.f (which determines the cross sections) and
87              complete_recon_ev (which calculates physics quantities from the reconstructed
88              tracks) are user routines.  They have reasonable starting cross section models
89              and event reconstruction, but it is important that you verify that the
90              physics variables are reconstructed in a way consistent with your analysis of
91              the data, especially when it comes to things like energy loss corrections, 
92              raster corrections, etc....