1. Detector Upgrades and Responsibilities Hampton University, Hampton, VA 23668, USA BLAST@DORIS Workshop, DESY, March 31, 2008 Michael Kohl

2. Proposed Experiment Electrons/positrons (100mA) in multi-GeV storage ring DORIS at DESY, Hamburg, Germany Unpolarized internal hydrogen target (buffer system) 3x10 15 at/cm 2 @ 100 mA → L = 2x10 33 / (cm 2 s) Large acceptance detector for e-p in coincidence BLAST detector from MIT-Bates available Redundant monitoring of luminosity pressure, temperature, flow, current measurements small-angle elastic scattering at high epsilon / low Q 2 Measure ratio of positron-proton to electron-proton unpolarized elastic scattering to 1% stat.+sys.

3. OLYMPUS pOsitron-proton and eLectron-proton elastic scattering to test the hYpothesis of Multi- Photon exchange Using DoriS

4. Control of Systematics Luminosity monitors BLAST @ DORIS 10 o Change BLAST polarity once a day Change between electrons and positrons once a day Left-right symmetry

5. Control of Systematics i = e+ or e- j= pos/neg polarity Geometric proton efficiency: Ratio in single polarity j Geometric lepton efficiency:

6. Control of Systematics Change between electrons and positrons every other day Change BLAST polarity every other day Left-right symmetry Super ratio: Cycle of four states ij Repeat cycle many times

7. Luminosity Monitoring Measure L ij relative and continuously Pressure, temperature, flow, current measurements Forward-angle (high-epsilon, low-Q) elastic scattering (  e+ =  e- ) Moller scattering … At forward angle:

8. Forward Elastic Luminosity Monitor Forward angle electron/positron telescope with good angular and vertex resolution Coincidence with proton in BLAST High rate capability GEM technology? MIT protoype: Telescope of 3 Triple GEM prototypes (10 x 10 cm 2 ) using TechEtch foils F. Simon et al., IEEE2007, arXiv:0711.3751

9. Forward Elastic Luminosity Monitor Two symmetric GEM telescopes at 10 o Sub-percent luminosity measurement per hour for all energies 22.5 msr = 30 x 30 cm 2 at 200 cm distance Two GEM layers with ~0.1 mm resolution with ~10 cm gap → Vertex resolution (z) of ~1cm at 10 o Two-photon effect negligible at high-  / low-Q 2

10. MIT GEM-Lab GEM R&D at MIT Laboratory for Nuclear Science (LNS) and MIT-Bates Linear Accelerator Upgrade of STAR forward tracker Richard Milner (Principal Investigator) Bernd Surrow (Assistant Professor since 2003) Douglas Hasell (Principal Research Scientist) Frank Simon (Postdoc, previously COMPASS) Jim Kelsey (MIT-Bates Mechanical Engineering) Miro Plesko (MIT-Bates Electronic Engineering) F.S. now Junior Group Leader at MPI Munich

11. HU Nuclear Physics Group Cynthia Keppel (Endowed Professor) Eric Christy (Associate Professor) Rolf Ent (Adjunct Professor) Antje Bruell (Adjunct Professor) M.K. (Assistant Professor) Howard Fenker (Jlab)

12. Providing GEM technology Collaboration HU-MIT Goal: Establish HU/Jlab GEM R&D Center –Howard Fenker / Bonus collaboration –Thia Keppel / Medical physics applications –Proton Cancer Therapy Center under construction at HU –Augment 12 GeV program at Jlab –By building C0 cylindrical GEM tracker for TREK, provide technology for 12 GeV program at Jlab –Luminosity monitors for OLYMPUS –Contributions to OLYMPUS further program?

13. Principle of GEM Detectors Copper layer-sandwiched kapton foil with chemically etched micro-hole pattern gas amplification in the hole GEM = Gas Electron Multiplier introduced by F. Sauli in mid 90’s, F. Sauli et al., NIMA 386 (1997) 531

14. GEM foils 70 µm 140 µm 70 µm 55 µm 5 µm 50 µm`` Typically 5  m Cu on 50  m kapton ~10 4 holes/cm 2 Chemical etching R. De Oliveira (CERN-EST) TechEtch (MIT, BoNuS) 3M Corporation Laser drilling Tamagawa (RIKEN)

15. Multi-GEM Detectors GEMs can be cascaded for higher gain Gain of 10 4 needed for efficient MIP detection Double GEM Triple GEM C. Buettner et al., Nucl. Instr. and Meth. A 409(1998)79 S. Bachmann et al., Nucl. Instr. and Meth. A 443(1999)464

16. TREK/E06 Tracking Upgrade  12 Planar GEMs (C1) between CsI and C2  1 Cylindrical GEM (C0) in replacement of former C1 70 µm 140 µm GEM technology Time Reversal Experiment with Kaons: Search for P T (K  3 )

17. C0 Cylindrical GEM for TREK 300 mm 140 mm160 mm

18. BoNuS Radial TPC (8-12 cm in./out. Diameter, 20cm active length) Ran in CLAS end of 2005, first experiment to use cylindrical GEM detector Further development planned for CLAS and Jlab-12 GeV → Howard Fenker H. Fenker et al., submitted to NIM (2008)

19. BoNuS Tag neutron initial momentum by measuring spectator proton at low momentum -> neutron structure Tag energetic pions by tracking low-momentum  ’s and tritons in pion production -> pion cloud study Barely off-shell Nuclear Structure

20. OLYMPUS Detector / Upgrades Crucial components for OLYMPUS BLAST core detector (WC+CC+SC) Additional e+,e- discrimination? Luminosity monitoring

21. Further use of BLAST @ DORIS Polarized H/D target (ABS) Neutron detectors Recoil detectors Inner tracker Forward-angle tracking Forward tagging system/quasireal photons

22. OLYMPUS Responsibilities DORIS - DESY Transfer of BLAST detector – MIT/Bates BLAST Cerenkov counters – ASU BLAST Time-of-flight scintillators – UNH Unpolarized gas target – MIT/Bates Luminosity monitors – HU/Jlab Electron/positron ID Maintenance and operation of detector components Simulation tasks Analysis tasks