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Amasim and Photonics. 2 nd edition. Stephan Hundertmark Bartol 22 March 2004. History behind this implementation. First implementation was slow, due to treatment of muons as many point sources Workshop in Laguna Beach (2003) showed great intrest to solve

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Amasim and photonics




2nd edition

Stephan Hundertmark

Bartol 22 March 2004

Amasim and photonics

History behind this implementation

First implementation was slow, due to treatment of muons as

many point sources

Workshop in Laguna Beach (2003) showed great intrest to solve

this problem

Ped 'integrated' the photonics tables to get infinite muon tables

the so called level2 photonics

In the implementation the photonics coordinate system was changed

Traditionally we talk about photonics a lot (it makes good workshops),

but we never got it going

We hope that the photonics treatment of the photon propagation will

solve our ice related problems

Amasim and photonics

Current Situation

There are two interfaces to photonics availible:

1.) PSI in development by Thomas Burgess

2.) Scatserver developed by SH

This is about the scatserver implementation

Scatserver wraps the photonics call functions into TCP/IP calls

Amasim and photonics

General Idea

Implement the geometry conversion (amasim->photonics)

Do low level checks, simple test cases for geometry

Compare PTD bulk tables to photonics bulk tables

=> same input should produce same output

The basic test is to compare the mean amplitude per OM for showers

There is nothing like the same tables for PTD and photonics

We check the mean of the mean amplitude per OM for many

showers from a test stand, PTD and photonics runs on the same inputfile

Main Goal: Solve our Ice related problems

Amasim and photonics

The test stand:

Isotropical distributed

epairs of 10 GeV in a

100 m sphere

The single downlooking

OM is moved from the

center of the sphere

to +/- 100 m

and +/- 200 m


Amasim and photonics

What does the result look like -- 1st attempt

Used the bulk ice

s=24m f=0.96

for ptd


a bulk ice table

from photonics that

I had laying around

on my hard drive



What does this mean ?

Photonics interface

wrong ?

Table wrong ?

Both ?

PTD interface wrong ?

Amasim and photonics

Let's try a new table...

This is a photonics

table I got from


(No blame here !)



Wow !

=> need to figure

out what tables

are used, ie. how

they are produced


I wanted to program

the amasim interface

not work with photonics

Amasim and photonics

Produced my own set of bulk tables:



- increased the dimensions

of the generation volume

- ptd like absorption

=> this looks already

much better

Amasim and photonics

Changing the variable we look at: amplitude vs. distance



...more intresting

is the ratio



Amasim and photonics

The ratio is nearly constant

as a function of distance

Why is the ratio not 1 ?

There are some efficencies

Glass, Gel, QE ...

What are the ptd settings

for these efficencies...

The statistics here was

1e7 photons

OM @ z=0

OM @ z=100

OM @ z=-100

OM @ z=200

OM @ z=-200

Amasim and photonics

List of efficencies from photonics README.eff

  • Glass index of refraction

  • Glass type (Benthos, Billings)

  • Gel index of refraction

  • Gel type

  • Sensitivity, angular

  • Quantum efficency model

  • OM curvature correction

  • Dynode efficency

What are the ptd settings

for these efficencies ?

Made an educated guess ...

Amasim and photonics

The ratio using my best guess for ptd settings in photonics

Striking result:

=> By just changing

the efficencies

the mean amplitude

changes by ~30%


Which efficency

has the largest

impact ?

Is there one

dominating ?

Amasim and photonics

Went through the efficencies one by one always changing

from the 'ptd-settings' only this one while retaining the rest

Largest change in glass:

Benthos describtion

from dada_attn

to Peter S. measurments

then next largest is

the description of the


large uncertainties from

input parameters we don't

fully know

Amasim and photonics

Conclusions for amasim/photonics interface

there had been extensive debugging and comunication

with Ped about the coordinates

all test make sense by now

the amasim/photonics interface works

shown for the (shower) amplitudes but as

coordinates are the same for muons and time

access, the risks for surprises are low

the next step is to check the timing distributions

-> need for new tables

after this muons and ice-layers ...

there is a need for a more convenient comparison

method between ptd/photonics tables

this should not need to be done via amasim

ultimatively we want

to use Thomas PSI