The GEANT user subroutines describing MILAGRITO are in
short int nPMTs
(number of PMTS)
Two important parameters are
waterlevel (180 cm)
and
coverlevel (190 cm)
in ugeom.f.
If coverlevel exceeds waterlevel (default),
then the air between water
and cover is dielectic, thus taking into account total internal reflection
for upward going Cherenkov light.
The following plots show the dependance of the "late light tail" on parameters
of the MC. Fig. 1 shows the chi(time) for
tubes with less than 1.5 pes for the experimental data (Run 558),
Fig. 2 for the MC without total internal reflection and
5 % bottom reflectivity, Fig. 3 includes total internal
reflection, and for Fig. 4, the bottom reflectivity is 10 %
(see Fig. 5 for a superposition of these plots).
The slope of the fitted exponential goes from 0.051 to 0.043 and 0.038, which is still
higher than the data with 0.032.
/disk02/Milagro/simulation/milagrito_geant/
together with a
makefile
and a program to convert the GEANT output into the current milagrito
data format (
rewrite_mc
).
The makefile produces the executable
milagrito
which needs the steering file
card:
milagrito < card
Right now, the input file has to be a CORSIKA file. The subroutine
getparticle.f reads the CORSIKA file given as the last line of the
steering file
card
.
The meaning of (some) of the parameters in card (1=on, 0=off):
ckov
production of Cherenkov light
hadr
hadronic interactions
dray
delta ray production
labs
Cherenkov light absorption
cuts
energy cuts (in GeV) for the different particle types.
The other parameters refer to physical processes like
Compton scattering, pair production, bremsstrahlung. Please
check the GEANT manual
for details.
Make sure that the third
time
parameter is equal or greater than the number of
events in trig.
If you want to see particle tracking "live" (very slow, but interesting),
change the view parameter (first line)
in card and make sure that the NGBANK parameter in milagrito.f
is increased to (at least) 7000000.
Units are GeV, cm, g, and radians. As output, milagritosim gives the
number of tubes, and for each tube the pulseheight and the time. The
time is given with respect to the time of the first hit which is set to
1. In addition, the height of the first interaction is given.
The default output file of milagritosim is fort.30, the default output file
of rewrite_mc is mcdata.dat.
After running rewrite_mc, the tube information is stored in the
CAL_DATA structure (see /disk02/Milagro/analysis/offline_v21/procData.h).
Additional information is in the MONTE_INFO structure. Currently,
the following information is stored:
short int MONTE
(1 for MC, 0 for experimental data)
unsigned int eventNum
(event number)
unsigned int triggerId
(1 for gamma showers, 14 for protons, 5 for muons)
float xCoreMC, yCoreMC
(true core position in cm)
float thetaMC, phiMC
(true zenith and azimut angle in rad)
float sizeMC
(number of shower particles at observation level (gammas, electrons, muons, hadrons))
float ageMC
(height of the first interaction in cm)
float muonMC
(number of muons entering the pond)
float ePrimary
(energy of the primary particle in GeV)
The final output can also be displayed using Gus' event display program
(~gus/openGL/GLUT/newDisplay).
Currently used parameters
Changing the absorption length from 10m (at the maximum) to 5m gives a slope of 0.06
(see Fig. 6),
and there is no way to get the late light tail of the data with using only 5m absorption length.
This leaves us with at least
three parameters to play with (absorption length, bottom reflectivity, and
cover reflection (with or without total internal reflection)), and an unknown
parameter not yet implemented (the scattering of Cherenkov photons).
Monte Carlo library
