DVCS – Hall ADVCS – Hall A

Study of the Study of the Background NoiseBackground Noise

HUGS 2008

Florian ITARD

University Blaise University Blaise PascalPascal

Clermont-FerrandClermont-Ferrand

Laboratory of Corpuscular Physics (LPC)

Deeply Virtual Compton ScatteringThe simplest experiment to access to the GPDs

Small cross section ~ 10-9 Barn

Latest experiment ran in 2004Next experiment will run in may 2009

Exclusive experiment

Spectrometer

Up beam tube pipeDown beam tube pipe

Scattering chamber

Proton array

Calorimeter

Target

High luminosity ~ 2.5*1037 cm2.s

Important background noiseProduction of a continuous signal in the photo-mutipliers which is going to inconvenience the measure

Appeareance of a darkening in the cristal

Systematic errors

New calibration

yelded light undervalued

Curing?

Simulation Monte Carlo: GEANT 4

One aim: Reduce the background noise without change the place of the calorimeter in the last experiment

New detector simulation toolkit written in C++ and developped by The CERN collaboration

Enable to generate any particules and follow them in the geometry of the experiment

10 Millions electrons generated by run

9 hours calculation in a farm

Window of 640 ns

Reference results

Mean energy deposited by each electron reaching the target (KeV)

Cone beam pipe

Rectangular beam pipe

Tungsten shielding

Polyethylen front shielding

Final resultsMean energy deposited by each electron reaching the target (KeV)

Mean energy fonction on the depth of the block

Curing ?

THE END