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Results From the Radphi LGD

Results From the Radphi LGD. Dan Krop 12/11/03. The Radphi Experiment. Radphi Experiment Took Data in Jlab Hall B From May to July 2000 962 Hours Of Beam Written To Disk 700 M Triggers Recorded Radphi was a g p->Xp Experiment. JLab End Station. 40m photon beam path. radphi detector

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Results From the Radphi LGD

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  1. Results From the Radphi LGD Dan Krop 12/11/03

  2. The Radphi Experiment • Radphi Experiment Took Data in Jlab Hall B From May to July 2000 • 962 Hours Of Beam Written To Disk • 700 M Triggers Recorded • Radphi was a gp->Xp Experiment

  3. JLab End Station 40m photon beam path radphi detector location e- beam from accelerator electron beam dump photon tagger

  4. 620 element downstream calorimeter Detector Apparatus 8 paddle upstream charged particle veto 70 cm Be target downstream charged particle detector wall 4 inch lead shield to protect detectors from beam halo target region barrel shaped charged particle detection and 24 element calorimeter

  5. Beam Energy • Radphi is a low energy/large angle experiment • Electron beam energy was 5.65 GeV • Brehmsstrahlung photons were from 75% to 95% of electron energy - 4.24 GeV to 5.37 GeV

  6. Photon Angles • LGD was ~ 1 m downstream from target • many large angle events

  7. Radphi situated behind CLAS • Material around the beam from interactions with upstream apparatus • Beam not as well collimated as Hall D will be • Brehmstrahlung angle ~ • Even with the EM background, the LGD performed well. Run Environment

  8. Lead Glass Detector 620 lead glass blocks 4x4x45 cm 15 radiation lengths light collection by Russian FEU-84-3 phototubes powered by custom Cockroft- Walton bases 8cm diameter beam hole subtends angles out to 27 degrees from the beam direction Glass recycled from BNL E852

  9. 2 Photon Events

  10. 3 Photon Events

  11. 4 Photon Events

  12. LGD Energy Resolution • Combined Resolution Study on Single h & p • Includes spatial terms

  13. Conclusions • Pb/Glass Calorimetry is possible in noisy brehmsstrahlung environment • LGD key component in L2 and L3 trigger • Identification of exclusive final states • With run conditions worse than GlueX will have, Radphi was still able to get good calorimeter performance

  14. Backup Slides

  15. Three Level Trigger (tagger-BSD coincidence) Rate=600k/s Level 1 (tagger-BSD coincidence+ not busy) rate: 274,000 Hz Level 2 (any LGD channel above a threshold) pass rate: 8000 Hz 1.2 s dead time 32% dead time contribution Level 3 (digitized energy sum) pass rate: 350 Hz 8-12 s dead time 8% dead time contribution Basic interaction trigger L2 modules designed and built at IU for radphi L3 module designed and built At IU for E852

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