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Electron detectors for HAPPEX2 and He

This project focuses on developing, testing, and installing electron detectors for high-energy experiments like HAPPEX2 & He 4. The detectors are designed to handle high-energy electrons, undergo PMT tests, and are radiation-hard for various experiments. The geometry of the detectors, made from magnetic materials, ensures accurate measurements with negligible asymmetry contributions. Utilizing Moeller dipole for testing with high-energy electrons, the project aims for precise resolution and corrections to enhance the final results. Real data analysis and PMT tests with details on gain ranges and running conditions are also crucial components. Detailed installation procedures in the HRS setup and efficient handling of the detector assembly ensure smooth functioning and data collection for this important scientific project.

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Electron detectors for HAPPEX2 and He

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  1. Electron detectors for HAPPEX2 and He 4 • Design • Tests with high E electrons • PMT tests • Installation in HRS

  2. Focal plane Detector t = 65 Mhz Dose = 2 MRad

  3. 100 x 600 mm Geometry Detector stack overlaps elastic line Two segments geometry for HAPPEX2

  4. Mechanics 5 inches PMT Brass-quartz stack Light guide Filter box

  5. Fused quartz • Radiation hard (Babar, CMS, E158) • Optical polished • (15-20 Angstr) • 92% transmission in the range • [350,550] tested with optical • bench and with cosmic rays

  6. Magnetic materials Bext False asymmetry Fe Fe N+ N- FA= M(Fe) x P(Fe) x <A> Polarized electrons M(Fe) -> specified ~ 1% P(Fe) -> a) Bext at focal plane b) mr <A> Mean Moeller asymmetry -> numerical calculations.

  7. Magnetic materials • -Bext <= 0.4 Gauss, mr <=2 • PFe < 10-5 -<AMoller> << 1 ppm • -Negligible contribution in • the detector asymmetry.

  8. Test with high energy electrons Moeller dipole Beam pipe h2 h1 Motorized rail Trigger scintillators Hodoscope Selection of 2 e- of same energy

  9. Resolution • Nge/e- = 250 DE/E = 18 %

  10. 100 x600 mm Edge Effects DE/E=20% • Larger resolution balanced • by extra statistics. • Need to correct for • correlations between two • segments for final result. Real data to be analyzed DE/E=90%

  11. PMT tests • PMT burle 8854 • Need wide range in gain • (10E3-106) : • 2 bases available: • - Happex • - Resistive, low gain

  12. PMT test Gain/IAnode correlations Running conditions: Preliminary results: 40 MHz, Filter 1/10 25 ge/e  I=1mA with G=104 -Happex Base DG/G =5% @ 1170V -Resistive base: DG/G= 2%@ 1420V

  13. Horizontal rails Installation in HRS

  14. Installation in HRS

  15. Installation in HRS 10 cm vertical gap between VDC and detector for scanners

  16. Detector Change • Remove 1 segment in each spectro. ~4h • Start installation of previously prepared “L” detector. • Assembly of the 2 removed segments for the 2nd “L” ~8h • Installation of the 2nd “L” ~6h • Could be done within 1 day Man power : 5

  17. WEB Eveything at: www-dapnia.cea.fr/Phys/Sphn/Parity/

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