A Digital Hadron Calorimeter ? Vishnu V. Zutshi NIU/NICADD

The proposal Development of New Hadronic Calorimetery Technology G. Blazey, D. Chakraborty, A. Dyshkant, M. Martin, V. Rykalin, V. Zutshi NIU/NICADD A. Brandt, K. De, A. White, J. Yu UTA Arrive at a realistic cost estimate for one of these devices

From analog to digital Eflow seems to be a promising option for improving jet resolutions significantly ALEPH and CDF have successfully used it Requires a high granularity calorimeter Digital hadron calorimeters: high granularity at affordable price ?

General Considerations Granularity (energy and resolving power) MIP recognition Absorber density (optimize shower lateral size) Depth Matching to EM calorimeter Readout (2d preferred to strip type) Minimal intrusions

Energy and position

Too much of a good thing?

Analog and Digital 20 GeV pions in SD

Single Particle Resolutions

On the software side of things Prototype simulations: try out different cell shapes parameterized losses from test stand hoping to do this in GEANT4 framework Event generation and LC detector simulation Eflow algorithm development starting with the EM section

The Algorithm (cal-seeded) Layer-by-layer clustering based on a search for local maxima Cluster definition based on nearest neighbour Track extrapolation through the calorimeter picking clusters in its path EM/HAD. Charged/neutral discrimination Understanding of errors involved with the tracking and calorimetric measurements

Sanity Checks hits clusters

Initial concept (scintillator-based) Four concentric layers of towers (7 stacks of 6-12 cells to a tower) formed with hexagonal cells. Start with 9cm 2 cell.

Initial concept (scintillator-based) Conversion to current: VLPC’s APD’s MRS’s PMT’s Cost per channel v/s S/N

Test stand Cell with WLS fiber irradiated by a radioactive or LED WLS fiber connected to clear fiber which is connected to a photodetector (PMT’s, VLPC’s etc.) Output measured by a Pico ammeter

Test goals Find minimum area/thickness of cell Find minimum length of WLSF Measure signal losses at the WLSF to clear fiber transition

MIP signal With VLPC readout 9mm thickness,0.5mm fiber,2optical connectors

Initial concept (gas-based) GEM approach Developed initially for MSGC’s Can be used with printed circuit readout GEM’s with gains above 10 4 and spark probabilities < have been developed Reasonably fast operation Relatively low HV

Initial concept (gas-based)

Issues/concerns (gas-based) Cost of GEM layers Lifetime/damage to layers Effects of highly ionizing particles Gas(es) ? Mechanical stability of GEM gaps/supports Cross-talk …..

Summary Single cell characterization studies have begun GEM based feasibility studies starting soon Event generation and simulation server ready Setting up for GEANT4 based prototype simulation studies Eflow algorithm development underway