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Rearrangement of the A4 Calorimeter for the Backward Angle Measurement. Outline. Rearrangement of the Experimental Setup Electron Tagging Counter Summary and Outlook. Rearrangement of the Experimental Setup. Calorimeter. Scattering Chamber. Target. Luminosity Monitors.
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Rearrangement of the A4 Calorimeter for the Backward Angle Measurement B. Gläser, PAVI06
Outline • Rearrangement of the Experimental Setup • Electron Tagging Counter • Summary and Outlook B. Gläser, PAVI06
Rearrangement of the Experimental Setup B. Gläser, PAVI06
Calorimeter Scattering Chamber Target Luminosity Monitors Scattering Geometry under Forward and Backward Angles Scattering Chamber Elongation B. Gläser, PAVI06
New Support Rotatable Calorimeter and Scattering Chamber Support Plane Steel Plate Hydraulic Oil Plunger B. Gläser, PAVI06
New Rotatable Calorimeter B. Gläser, PAVI06
Rearrangement Movie B. Gläser, PAVI06
255 MeV 315 MeV 570 MeV First Measurements at Backward Angles 225 MeV B. Gläser, PAVI06
g e- Background Simulation Simulated Photon Background @ 315 MeV from p0 Decay B. Gläser, PAVI06
Electron Tagging Counter B. Gläser, PAVI06
Counter Geometry and Efficiency PbF2-Crystal … … e- e+,e- Additional Counter g Scattering Chamber Electron Beam Efficiency Demands on the Counter: Detection Efficiency Electrons -> 100% Detection Efficiency Photons -> 0% Elastic Rate @ 20µA (One Crystal): ~ 1,1 kHz B. Gläser, PAVI06
Counts Pulse Charge / a.u. Cherenkov Counter vs. Scintillator Scintillator Pulse Height Spectra Cherenkov Pulse Height Spectra Counts Pulse Height / a.u. Detection Efficiency Electrons: Detection Efficiency Photons: Radiation Length Counter and Scattering Chamber: < 100% ~ 0% ~ (10,1 to 14)% X0 ~ 100% > 0% ~ 15% X0
Counter Types • Diffusely Reflective Aerogel Cherenkov Counter • Gas Cherenkov Counter • Scintillation Counter B. Gläser, PAVI06
Diffusely Reflective Aerogel Cherenkov Counter CalorimeterCrystals Housing Window for Photomultiplier Housing Aerogel ScatteringChamber Target Centerline Scattering Chamber Aerogel
Gas Cherenkov Counter GasCherenkov AerogelCherenkov Filling: Refractive Index: Expected Photelectrons: Isobutane 1,0019 ~4 Aerogel (High Transparent) 1,05 ~5 B. Gläser, PAVI06
Scintillation Detector Plastic Scintillator (EJ-204) Photomultiplier Housing (XP2262B) Scintillator Dimension : 20 mm x 50 mm x 400mm B. Gläser, PAVI06
Energy Spectra @ 315MeV with the Tested Counters Aerogel Gas Scintillator Counts ADC-Channel ADC-Channel ADC-Channel Elastic Efficiency: ~68% ~46% ~81% Covered PbF2-Crystals: 28 28 14 Expected Elastic Rate: ~30kHz ~30kHz ~15kHz Measured Total Rate: ~2Mhz ~800kHz ~3Mhz
The New Scintillation Counter Scintillator Photomultiplier Base Scintillator: Plastic Scintillator EJ-204 from Eljen Technology Photomultiplier: A Standard Fast, 12-Stage, 51mm Tube XP2262B Base: Full Active Base, our Design B. Gläser, PAVI06
Final Design Double Ring with 72 Scintillator Modules. Each Module Covers 14 PbF2 -Detectors
Final Calorimeter Design B. Gläser, PAVI06
Histogramm Unit MEDUSA Pola-Bit data signal processing Memory pol0 pol1 PbF2 PM trigger Scintillator pol0* pol1* unused Adress bit PM CFD progr. Delay 20 ns Counts Delay / ns Electronic Setup Typical Rate Scintillator: ~ 1MHz Accidential Coincidence: 1% - 4%
PRELIMINARY Actual Energy Spectra @ 315 MeV Counts Counts / 103 Counts ADC-Channel Elastic Efficiency : ~90% ADC-Channel B. Gläser, PAVI06
Summary and Outlook • Rearrangement of the Calorimeter Setup • Electron Tagging Counters Tested • New Scintillation Counter • Measurements at Backward Angles • Measurements with Deuterium B. Gläser, PAVI06