1 / 26

Title Slide!!

Title Slide!!. HBD. Di-lepton Physics. Diverse Physics: Vector Mesons Dalitz Correlated semi-leptonic decays. Chiral Restoration?? Staple in High Energy Physics. Arguably the most difficult measurement in Heavy Ion Physics. Invariant Mass Spectrum from e + e -. relativistic electrons.

auryon
Download Presentation

Title Slide!!

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Title Slide!! HBD Jason Kamin May 17th, 2006

  2. Di-lepton Physics • Diverse Physics: • Vector Mesons • Dalitz • Correlated semi-leptonic decays. • Chiral Restoration?? • Staple in High Energy Physics. • Arguably the most difficult measurement in Heavy Ion Physics Jason Kamin May 17th, 2006

  3. Invariant Mass Spectrum from e+e- relativistic electrons φ π photoelectron blob All Pairs Combinatorial Pairs Signal Pairs >100x • Major problem: Huge combinatorial background mostly due to: • γ-conversions & π0 Dalitz decays. • We need a new detector, that can ID e’s from these two sources. • Full ID of background: eID & chargeID & (minv < mπ) • Good enough: eID & P-hat (two e’s with small opening angle) • Hadron-Blind Detector: • Cherenkov for eID. • Field free region of PHENIX (p-hat) Field can be canceled in a small region around beampipe. Lighter particles have smaller opening angles!! Jason Kamin May 17th, 2006

  4. Unfocused Cherenkov “Blobs” • No room for traditional optics (ie. focusing mirror). • Cherenkov light collected as an unfocused blob. • 1.5 m^2 photosensitive region • Low radiation length: • minimize photon conversions. • Charged particles from collision will pass through: • ionization must not interfere with photoelectron detection. Cherekov Radiation e- • Can YOU design this detector??? (r,phi) – bins grow with radius (x,y) – uniform bins Jason Kamin May 17th, 2006

  5. Gas Electron Multiplier (GEM) • The original idea by F.Sauli (mid 90s) US Patent 6,011,265 • Traditionally CHARGED PARTICLE detectors (not photons) 150μ • Two copper layers separated by insulating film with regular pitch of holes • HV creates very strong field such that the avalanche develops inside the holes • Just add the photocathode • By the way: no photon shine back onto photocathode Jason Kamin May 17th, 2006

  6. The concept HV ~150 μm • Get a GEM • Put a photocathode (CsI) on top • photoelectron from Cherenkov light avalanches in the high density E-field • Use more GEMs for larger signal • Pick up the signal on pads • What about ionizing particles (hadrons)? • We need a mesh with a reverse voltage on it to blow electrons away!!! • We have a detector sensitive to UV and blind to ionizing particles! Jason Kamin May 17th, 2006

  7. Hadron Blindness:UV photons vs charged particles • At slightly negative Ed, photoelectron detection efficiency is preserved whereas charge collection is largely suppressed. • Charge collected from ~150μ layer above top GEM Jason Kamin May 17th, 2006

  8. The HBD Detector HBD Gas Volume: Filled with CF4 Radiator (nCF4=1.000620, LRAD=50 cm) Windowless Cherenkov Detector Radiator gas = Avalanche Gas Cherenkov light forms “blobs” on an image plane (rBLOB~3.36cm) e+ e- q Pair Opening Angle 55 cm Pcb pad readout (~ 2x2 cm2) 5 cm Electrons radiate, but hadrons with P < 4 GeV/c do not CsI photocathode covering GEMs Triple GEM detectors (12 panels per side) Space allocated for services Dilepton pair Beam Pipe Jason Kamin May 17th, 2006

  9. evaporator glove box laminar flow hood GEM storage vessel The Clean Tent at USB Level of Clean Room Entrance Foyer Jason Kamin May 17th, 2006

  10. The Evaporator on loan from INFN Roma Magnetically coupled driver for moving the GEMs inside the vacuum. Quantum Efficiency Station Evaporation Chamber Jason Kamin May 17th, 2006

  11. Harpoon for moving mounting box GEM mounting box w/ wheels on track GEM CsI The Evaporation Chamber Molybdenum boats • Boats are in series so they must be brought up to temperature slowly (~10 min) • 250 – 450 nm layer of CsI at rate of ~2 nm/sec • ~24 hrs to pump down vessel • vacuum ~10-8 mbar • no water!! • Evaporate 4 GEMs simultaneously AC Jason Kamin May 17th, 2006

  12. GEM w/ CsI e- ampmeter e- ~ 100 V ~ 2mm Xe lamp MgF2 window (λ=160,185,200 nm) mesh (e- collection) γ mirror reference PMT The Quantum Efficiency Station Harpoon for moving mounting box GEM mounting box w/ wheels on track GEM with CsI Molybinum boats AC Jason Kamin May 17th, 2006

  13. 40 Relative QE (%) 0 x-coordinate across GEM Quantum Efficiency • Excellent QE. • Comparable to best in the world. • QE constant across GEM. • It’s crucial to maintain high QE after production. Jason Kamin May 17th, 2006

  14. 55Fe Jason Kamin May 17th, 2006

  15. Jason Tom Liz Bill Summary • Hadron Blind Detector is crucial to the low-mass dielectron spectrum. • Excellent QE is achieved at the Stony Brook production facility. • The HBD prototype is installed in PHENIX and being tested. We have seen the light!! (it’s working). • Final HBD is scheduled to be installed in late Aug 2006. Jason Kamin May 17th, 2006

  16. The PHENIX HBD Collaboration A.Dubey, Z. Fraenkel, A. Kozlov, M. Naglis, I. Ravinovich, D.Sharma, I.Tserruya Weizmann Institute of Science B.Azmoun, D.Lynch, R.Pisani, C.Woody Physics Dept., Brookhaven National Lab J.Harder, P.O’Connor, V.Radeka, B.Yu Instrumentation Division, Brookhaven National Lab W. Anderson, A. Drees, J. Franz,T. Hemmick, R. Hutter, B. Jacak, J. Kamin, M.McCumber, A. Milov, A. Sickles, A.Toia Stony Brook University C.-Y. Chi Nevis Labs, Columbia University H. Hamagaki, S. Oda, K. Ozawa University of Tokyo L.Baksay, M.Hohlmann, S.Rembeczki Florida Institute of Technology D. Kawall Riken M. Grosse-Purdekamp University of Ilinois

  17. Conclusions (not mine, stolen. Needs work. ) • Strong hadron rejection can be achieved with good photoelectron efficiency • High gain/stable GEM operation can be obtained in pure CF4 • A windowless Cherenkov detector can in principle achieve a very high N0 when used in conjunction with a with deep VUV transmitting gas such as CF4 However, impurities such as O2 and H2O can cause a significant loss of Cherenkov light (O2 and H2O must be kept at the few ppm level) • GEM detectors work in the high multiplicity environment at RHIC • No significant aging effects are observed in either GEMs or CsI photocathodes for intergated charges well in excess of what is expected to be reached at RHIC • Need to meaure N0 in a realistic detector and test a fully functional prototype in the PHENIX Jason Kamin May 17th, 2006

  18. Final HBD Exploded view Design parameters: • Acceptance at nominal position: || ≤0.45, =1350 • Acceptance at retracted position: || ≤0.36, =1100 • GEM size: 22 x 27 cm2 • # of detector modules per arm: 12 • GEM frame: 5 mm wide, 0.3mm cross • Hexagonal pad size: a = 15.6 mm • Number of pads per arm: 1152 • Dead area within acceptance: 6% • Rad. length within acceptance: box: 0.92%, gas: 0.54% • Weight per arm: <10 kg Jason Kamin May 17th, 2006

  19. HBD Response Simulation Includes 20 cm absorption length in CF4, lamp shadowing, realistic losses and conservative N0 = 840 cm-1 Normal case, no absorption in CF4, no lamp shadowing, realistic losses and conservative N0 = 840 cm-1 Total signal: 38 e = 29 (dE/dx) + 9 (Cherenkov ) Blob size: single pad response =78%  very similar to data Total signal: 62 e = 29 dE/dx + 33 Cherenkov Blob size: single pad 12%, more than one pad 88% Jason Kamin May 17th, 2006

  20. Aging Tests Test both GEM and CsI photocathode • Illuminate photocathode with UV lamp, • measure DC current to mesh • Measure gain with 55Fe source • Keep Imesh < 1 nA/cm2, gain ~ 5-10 x 103 • Continuously irradiate photocathode, • measure gain periodically • No significant aging effects of either the GEM or CsI photocathode • were observed up to ~ 150 mC/cm2 (~ 10 years at RHIC) • Gain was found to increase with exposure time • (Possible charging effect in GEM foils ?) Jason Kamin May 17th, 2006

  21. Clean Room Survey • Laminar Table Better than Class 1 • Foyer could be better (improve seal to main tent) • Dirty spot in the back (Air Conditioner filters!!!) Foyer Laminar Table ??? Outside Jason Kamin May 17th, 2006

  22. Jason Kamin May 17th, 2006

  23. AC Jason Kamin May 17th, 2006

  24. Jason Kamin May 17th, 2006

  25. D ED (+) G ET T G pA T ET G I EI ED = 0 Hadron Blindness: Response to Electronsdetector response vs ED at fixed gain • Charge collected from 150μ layer above GEM Efficient detection of photoelectrons even at negative drift fields Jason Kamin May 17th, 2006

  26. Pad Dimensions photoelectron blob 3.36 cm 2.74 cm 3.16 cm WHAT ABOUT A PICTURE OF A GEM HERE TOO!! Jason Kamin May 17th, 2006

More Related