Producing Efficiency Numbers for the DRAGON BGO Gamma Ray Array

The most current version of the GEANT3.21 DRAGON, BGO gamma ray array is
set to produce efficiency numbers for isotropic point source situated at
any position within the gas target. This version contains a version of
the array geometry accurate as of March 2005. The following procedure
will produce spectra or raw data numbers which will allow a user to
calculate the efficiency of the array for a given gamma energy,
threshold, and source position. Also possible is the calculation for a
situation involving a cascade. In this documentation the symbol "^"
represents the "ctrl key" on the keyboard.

1) Open a terminal on any linux machine and login to the "dragon"
account on ibm00.triumf.ca using a ssh connection.

2) Switch to the directory containing the array executable by using the
command: "cd gamdet/gbox_v5_trials/gbox_mod/v12"

3) Create a NEW directory in this location and copy all the files in the
subdirectory "sample" in the "v12" directory using the following
sequence: "mkdir datanamedir" "cp -r sample/* datanamedir" DO NOT ALTER
THE FILES IN THE SAMPLE DIRECTORY.

4) Your new directory should contain the following 4 files:
"go,convertdata.kumac,z0e500.ffcards,z0e535125.ffcards and 1 directory:
"rawdata"

5) To produce a simulation for the case of a single gamma ray, use an
editor such as "pico" to open the file z0e500.ffcards. e.g. "pico
z0e500.ffcards". This file contains all properties necessary to run the
simulation for your specific situation. 

6) There are 3 parameters in this file that should be altered in this
case. DO NOT ALTER OTHER PARAMETERS UNLESS YOU ARE FAMILIAR WITH
GEANT3.21 AND YOU KNOW WHAT YOU ARE DOING. IF YOU DO MAKE CHANGES LEAVE
THESE INSTRUCTION NOW AS THE RESULTS MAY NOT FOLLOW THE REST OF THE
STEPS.

a) The first parameter that should be altered is the "RUNG" parameter.
The current value should be "5000". The number gives a unique identifier
to the PAW hbooks or raw data files that will be produced with the
simulation is run. The number must be 8 digits or less.

b) The second paramter that can be changed is the "TRIG" parameter. This
should currently be set to 100000. This is the number of gamma events
that will generated by the source. This is sufficient for most purposes.
Note the value that this parameter is set to. It is the denominator in
the efficiency calculation.

c) The third paramater, "KINE", is near the end of the file. (Scroll
down using the arrow keys or ^v in pico.) This parameter contains 11
settings. The first parameter determines the number of gamma produced at
the origin. Shold be "1" in this case. The next three paramters
determine the origin in x,y and z of the source. For a source in the
center of the target these should all be set to "0". The next three
parameters determine the source distribution and should be all set to
"0" for a point source. Setting 8 is the energy of the gamma source in
MeV. Settings 9,10,11 determine the source emmittance and should all be
"0" for an isotropic distribution.

7) Once the changes are made save the file by giving it a unique name
AND the extension "ffcards". e.g. "z0e500.ffcards". Use ^o in pico. Exit
the editor. Use ^x in pico.

8) To run your simulation issue the simulation executable command:
"./go" You will be asked for the name of your ffcards file. Enter it
without the ffcards extension. e.g. "z0e500". The simulation will run
until all events are generated. You may run several simulations
simulataneously by issuing multiple "./go" commands. You may track the
progress of your simulation by using the following command: "tail -f
yourfile.log". Where "yourfile" is the name you saved your file with.
e.g. "tail -f z0e500.log". You will see the number of events generated
scrolling down the screen. Press ^c to exit.

9) Open PAW in a terminal using: "paw++&"

10) The simulation results can be analyzed using paw or taken to an
outside program by exporting the hbook spectra to a one column text
file. If you are going to export the data for use later then at this
point open the file in your directory called "convertdata.kumac". Modify
the line that begins with "hist/file 0 ..." so that paw searches in your
directory for the histogram files. e.g. change "sample" to
"yourdirectory". Modify the line "vec/write ..." similarily. Save and
exit. If you are going to analyze outside PAW++ skip to step 15 now.

11) In the "PAW++ Main Browser" window click on "Hbook" in the left
panel to bring up the list of hbooks. Find your hbook and double click
it. When you open the hbook it will be linked to a logic unit number or
LUN. These are shown in the same panel. Click on the appropriate LUN. 

12) Several spectra will appear in the right panel. Scroll through the
spectra until you reach number "200". Click on this spectra. It should
appear to your right in the "Paw++ Graphics 1" window.

13) The spectra are 1000 bins and 10.0 MeV full scale. Go the graphics
window and using the mouse click and hold on the bin that represents the
energy threshold you would like to use. Drag the mouse over the entire
spectra until you are beyond the full energy gamma peak. An information
window will come up telling you how many counts are in the area you
integrated. Use the "integration" number in the information window to
determine the counts.

14) Take this number and divide it by the number you found in step 6b.
This is the efficiency of the array for your conditions.

15) If you are analyzing outside PAW++ the spectra can be dumped to a on
column ascii file containing 1000 lines (one for each bin) where each
line is a number giving the number of counts in that bin. Click on the
"Macro" option in the Paw++ Main Browser window. You should see the
convertdata.kumac. 

16) Click on the convertdata.kumac macro to start it. The macro will ask
you for the histogram name "hisname" you would like to dump. Enter the
number you set in step 6a. You can continue to convert data. When you
are finished enter "quit" for the histogram name. The data will be
written to the "rawdata" sudirectory in your working directory. The
files will be given names in the form xxxxxxxx.dat. Where xxxxxxxx is
the number you entered in 6a. You can then use this data as you need it.

This information is current as of March 2005. Changes or improvements to
this procedure are welcome as long as they are thoroughly tested and
documented appropriately.

Send questions to: Dario Gigliotti (giglio0@triumf.ca).

Last Modified:

March 14, 2004 DG