Super-K Monte Carlo

Super-K Monte Carlo: Detector Simulation

Monte Carlo Simulations

Particle physics experiments make frequent use of Monte Carlo: detailed simulations of particle interactions and the resulting detector signals, incorporating known physical processes. Super-K is no exception. In Super-K, we simulate both neutrino interactions and background events in order to compare real data to expectation.

In general, particle physics experiment simulations take place in two steps.

  1. The first step employs a generator, or an "interaction generator". A generator simulates the interaction you are interested in, in the relevant material. For instance, for neutrino experiments, "neutrino generator" software simulates the charged particles that result from interactions of neutrinos with the detector material (say, water), given an input flux of neutrinos. Super-K uses two different generator codes: NUANCE, and NEUT. The output of a neutrino generator is a list of "vectors": it's basically a list of the particles that come out of a simulated interaction. For each outgoing particle, the list contains, at least: particle type, energy, direction, position (and sometimes other info). This list of generated particles is also referred to as a kinematics file.
  2. The second step is detector simulation. This takes kinematics files as input, and then simulates what the charged particles in each event would look like in the actual detector you have. Detector simulation software often makes use of packages like Geant (old, Fortran-based code), and Geant4 (a newer, C++ based package). Simulation of a particle in a detector is sometimes referred to as tracking, since the software tracks the particle's energy loss and trajectory in the detector.

    Super-K's standard detector simulation software is called skdetsim and it employs old Geant 3.

In this example you will start at the detector simulation step, and create by hand some kinematics files, and run them through skdetsim to create some SK MC events.


Before starting, you'll need to have run the usual Super-K setup stuff.
setenv PROJECT /var/phy/project/hep/neutrino
source $PROJECT/soft-SL6/SK-Duke.login

Files for this example

Copy the following files from

to your working directory:

Look at test.kin. This will be used as input to skdetsim. This contains the kinematics information (a "vector") for one event to be simulated, in Nuance format. It has:

$ begin 
$ vertex 0. 0.  0. 0
$ track 13 5000. 0. 0. -1. 0 
$ end 

Running this example is the script to use to run skdetsim in this example. It takes several arguments to indicate the input and output files. Run it as follows:

./ sk4_odtune.card test.zbs test.kin

After you have run this (it may take a bit of time to run), look at the generated output file test.zbs with superscan. Check that it indeed looks like a muon starting at the center of the tank and going straight down.

Stuff to try