CsI(Tl) Calorimeter and status of the E166 experiment E166 experiment CsI ( Tl) calorimeter construction. Test beam results vs. Geant4 simulation Schedules conclusion e+ K. Laihem ECFA-Durham, 03 September 2004 Cist) Calorimeter for E166

Experimental Demonstration for production of polarized e + Final focus test beam (FFTB) at SLAC with 50 GeV electrons 1 m long helical undulator produces circular polarized photons Undulator radiation 0-10 MeV (Balakin & Mikhailichenko 1979) Conversion of photons to positrons in 0.5 X0 Ti or W-target Measurement of polarization of photons and positrons by Compton transmission method Overview of E166 ECFA-Durham, 03 September 2004

Need for demonstration The production of polarized positrons, depends mainly on the polarization transfer from polarized photons in the conversion process (pair production). Fronsdal & Ueberall (1958); Olsen & Maximon (1959) In order to understand the experimental difficulties in undulator based production of polarized positrons we need the experiment The design of a linear collider (with or without polarized positron) may depend on this knowledge That it sufficient to demonstrate that undulator based production of polarized positrons works. ECFA-Durham, 03 September 2004

Compton scattering depends on polarization of photon and e - Either measurement of scattered photons or of unscattered photons: simpler setup Trasmission: Asymmetry: By knowing P e => P  can be calculated: Photon Transmission Polarimetry ECFA-Durham, 03 September 2004

Rotating magnetic field Wire wound helically Inner diameter 0.89 mm (E166) Magnetic field: 0.76 T (E166) Pulsed current: 2300 A Rate 30 Hz (E166) ParameterTESLAE166 Length~200 m1 m Beam~200 GeV50 GeV Period14 mm2.4 mm Strength K10.17 Cutoff~10 MeV9.6 MeV Positrons/ bunch 3 x x 10 7 The helical undulator ECFA-Durham, 03 September 2004

The helical undulator Pulse Generator Cooling system ECFA-Durham, 03 September 2004

Polarized Photons Conversion target Polarized Photons Vacuum chamber CsI ReConversion target e+ Undulator e- 50 GeV ECFA-Durham, 03 September 2004 Production and Diagnostics of polarized positrons Analyzing magnet SiW Calorimeter Two Diagnostic lines Gamma line Positron line

Polarized Photons Conversion target Polarized Photons Vacuum chamber CsI ReConversion target e+ Undulator e- 50 GeV ECFA-Durham, 03 September 2004 Production of Polarized photons Analyzing magnet SiW Calorimeter +1 Polarization Energy spectrum

Polarized Photons Conversion target Polarized Photons Vacuum chamber CsI ReConversion target e+ Undulator e- 50 GeV ECFA-Durham, 03 September 2004 Production of Polarized positron and Spectrometer Analyzing magnet SiW Calorimeter Polarization / dN/dE Positron energy (MeV) 5 MeV  70 %

Polarized Photons Conversion target Polarized Photons Vacuum chamber CsI ReConversion target e+ Undulator e- 50 GeV ECFA-Durham, 03 September 2004 Polarization Diagnostics Analyzing magnet SiW Calorimeter Photon energy (MeV) Polarization and counts 10 MeV positron on 0.5 X0 W 5 MeV Pol 

Polarized Photons Conversion target Polarized Photons Vacuum chamber CsI ReConversion target e+ Undulator e- 50 GeV ECFA-Durham, 03 September 2004

4 x 10 9 photons 4 x 10 5 e + 4 x 10 9 photons 4 x 10 7 photons ~ 500 TeV 5 x 10 4 phE 5x10 6 phE 1.6 x 10 3 photons of total ~ 6 GeV 2 x 10 7 e + Experimental setup ECFA-Durham, 03 September 2004

G1 + G1 - G32 + G32 - G1 + G1 - G32 + G32 - Photodiodes Preamp U-Mass receiver Board Amplifier Chan 1 Diff Amplifier 60 m Readout electronics

G1 + G1 - G32 + G32 - G1 + G1 - G32 + G32 - Diode B Diode A Diff Amplifier Gain 32 Gain 1 ADC

Test box and setup for QC CsI Calorimeter Construction Quality checking Wrapping the crystals ECFA-Durham, 03 September 2004

Light yield with respect different position of the 60 Co source along the Crystal UC03. Light yield with respect different position of the 60 Co source along the Crystal UC08. Cist) crystal Diodes 60 Co Lead collimator CsI Calorimeter Construction Quality checking ECFA-Durham, 03 September 2004

Light yield with respect different position of the 60 Co source all Crystals. Light yield statistics for all 9 Crystals using 60 Co source. CsI calorimeter Construction Quality checking Average light yield at 4600 Ph/MeV ECFA-Durham, 03 September 2004

Assembling the CsI Calorimeter Cooper foil wrapping and stacking the 9 crystals inside the brass housing ECFA-Durham, 03 September 2004

Test beam in DESZ Hamburg

Calibration/Cobalt source 60 Co Tall 03Tall 05

Geant4 one Crystal Test beam HH July 2004 Central crystal Calibration and Energy Deposition in the central crystal ECFA-Durham, 03 September 2004

Energy deposition Transition point (x 0 +t) Expo_Gauss Function Edep In one crystal calorimeter The function and its derivative are continus at the transition point

Correlation between the HG and LG HG LG Xtal01 Xtal08 Xtal04 Xtal05 Xtal02Xtal03 ECFA-Durham, 03 September 2004

Correlation between the HG and LG HG LG ECFA-Durham, 03 September 2004

Energy Resolution (testbeamHH/MC simulation) Geant4 simulation Prototype testbeam HH December 2003 TestbeamHH July 2004 ECFA-Durham, 03 September 2004

Comparison (testbeamHH/MC simulation) E dep with respect the beam energy Beam Energy (GeV) ECFA-Durham, 03 September 2004

ComponentStatusInstitution Helical undulator2x 1 m Ready (Tested) (soon at SLAC) „Cornell University“ Positron transport systemIn construction„Princeton University“ Analyzer magnetsReady (Tested) (In installation at SLAC) „DESY Hamburg“ CsI calorimeterReady (Tested) (In installation at SLAC) „DESY Zeuthen/ Humboldt University Berlin Si-W calorimeterReady (Tested) (In installation at SLAC) „University of Tennessee“ Aerogel countersReady (Tested) (soon SLAC) „Princeton University“ DAQ and ReadoutReady (Tested) (In installation at SLAC) „SLAC“ Status of Subcomponents ECFA-Durham, 03 September 2004

E166 is a demonstration of production of polarized positrons for future linear colliders Uses the 50 GeV FFTB at SLAC All prototypes work properly Installation of total experiment in FFTB tunnel in September 2004 First data taking run in October 2004 Second data taking in January 2005 Conclusions. ECFA-Durham, 03 September 2004 Geant4 simulation of the full E166 spectrometer Implementation of the linear polarization and polarization transfer in Geant4 Data analysis starting with the E166 experiment October 04  April 05 First published results by the end of next year