EHE MC check

In order to check the EHE MC, some data are generated and plots are made.


1. The data generation

In order to generate data, the JULIeT class are used. The weighting-module class is used to put weight and check the results. Note that the detector MC is not used in this check.

We generated 9 sets of data, namely, 3 different incident nadir angles and three different interaction combinations.

In one data set the incident nadir angle is at random (0-180 deg.), and others are somewhat fixed (0-18(upgoing), 162-180(downgoing) deg.). Azimuth angle is randomly selected as 0-360 deg. in any case.

We turned on the interaction of bremsstrahlung, pair creation, photo-nuclear and the decay. Then, in order to check the effect of interaction, we switched off the bremssrahlung and photo-nuclear interaction for two data sets respectively.

The other parameters are the followings.

The parameter of I3JulietPrimaryParticleSource

Min. Energy 6 [GeV]
Max. Energy 9 [GeV]
Differential Power Law Index 1
Inject Radius 880 [m]

2. The results

2.1. 0 < nadir angle (JULIeT def.) < 180 deg.

The primary particle info.


The maximum cascade position


The maximum cascade energy distribution (the default interaction)

The maximum cascade energy distribution (the default interaction - bremsstrahlung)

The maximum cascade energy distribution (the default interaction - photo-nuclear interaction)

There seems to be two bumps and two distributions. But, this may be physics. For me, it looks like the lower part of the distribution in the plot of the maximum cascade energy vs primary particle energy is due to the pair creation, and the other upper distribution is due to brems. and photo-nuclear. Because the brems. and photo-nuclear interaction is stochastic, so if the stochastic procedure doesn't take place, it would be natural that a cascade by a pair creation becomes the maximum one. I should have used only one interaction instead of switching off an interaction. I will try this.


The JULIeT differential flux Vs primary particle energy

The propagated flux Vs primary particle energy

It looks fine.


2.2. 0 < nadir angle (JULIeT def.) < 18 deg. (upgoing)

The primary particle info.


The maximum cascade position

Apparently, the z position of the maximum cascade is not symetric. This is upgoing case, so this will mean that the propagation length is not enough.


The maximum cascade energy distribution (the default interaction)

The maximum cascade energy distribution (the default interaction - bremsstrahlung)

The maximum cascade energy distribution (the default interaction - photo-nuclear interaction)


The JULIeT differential flux Vs primary particle energy

The propagated flux Vs primary particle energy


2.3. 162 < nadir angle (JULIeT def.) < 180 deg. (downgoing)

The primary particle info.


The maximum cascade position

This is just other way around compared to the upgoing case.


The maximum cascade energy distribution (the default interaction)

The maximum cascade energy distribution (the default interaction - bremsstrahlung)

The maximum cascade energy distribution (the default interaction - photo-nuclear interaction)


The JULIeT differential flux Vs primary particle energy

The propagated flux Vs primary particle energy


Problems to be solved


Follow-up

I switched only the pair creation interaction, and see what I expected. So, I would conclude that there is a physical meaning that we have two bumps in the maximum cascade energy distribution.

I tried to simulate data with only brems. and photo-nuclear interaction, but the program crashes. This may be related to the bug found in the hit-constructor, so I will update my codes, try it again, and will let you know.

However, still the distribution of the maximum cascade z position is asymetric. Strange.


Keiichi Mase
Last modified: Sat Sep 17 23:21:25 JST 2005