SHMS Aerogel Detector & Calorimeter Status A. Mkrtchyan 1
Super High Momentum Spectrometer Detector Hut Aerogel Detector Aerogel detector is situated between heavy gas (C 4 F 2 O) Čerenkov detector and S2 Hodoscopes of SHMS detector stack It will improve Kaon identification, expected Npe ~14 (SP-30 / 10cm) With dimensions 110x100x45cm, covers SHMS acceptance Possible 2 detectors Consists of 14 PMTs (plus optional 6 on top) and replaceable diffusion box with 10cm depth for different index Aerogel 2
Particle separation using Aerogel Detector Simulations done by S. Zhamkochyan 10 cm Aerogel n=1.030 10 cm Aerogel n=1.015 For K + /P separation at P > 3 GeV/c Aerogel detector is needed. In the momentum range 2-6 GeV/c separation is possible with two sets of aerogel detector (n=1.030 & 1.015). Above momentum 6 GeV/c aerogel material with lower index of refraction (n=1.010 and 1.006) will be needed. Electrons (positrons) are above threshold over essentially the full momentum range. Type of Particle P th n=1.030 P th n=1.015 P th n=1.010 P th n=1.006 μ 0.428 0.608 0.746 0.963 π 0.565 0.803 0.984 1.272 K 2.000 2.840 3.482 4.500 P 3.802 5.397 6.618 8.552 3
SEP and Cosmic with Bates & HMS Aerogel PMTs PMT Photonis XP4500B (#09630) from Bates SEP = 123.9-57.0= 66.9 Number of photoelectrons from cosmic: (571.5-58.3)/66.9 7.7 pe PMT Photonis XP4572 (#60105) from HMS Aerogel SEP = 101.5-57.1 = 44.4 Number of photoelectrons from cosmic: (605.9-58.5)/44.4 12.3 pe With Bates Photonis XP4500B PMT we have detected only ~7.7 pe from cosmic. We have compared QE of Bates PMTs with the HMS aerogel spare Photonis XP4572 PMTs. In general, all HMS Aerogel detector PMTs have quantum efficiency by factor 1.5-1.7 higher than Bates PMTs, but low gain. With HMS aerogel PMT we have detected ~12.3 pe from cosmic (~1.6 more). 4
Space preparation & clean room setup Prepared space in EEL room 126: stored boxed with PMTs and aerogels on shelves, all remaining aerogels kept unpacked inside BLAST diffusion boxes and moved to physics storage Reorganized Walters machine shop 2 nd floor: made mini-clean-room, filters changed. Will use this space for assembling and testing of aerogel detector. Currently setting electronics and DAQ.. Thanks to Steve Wood, Walter Keller and Walt Akers 5
Quantum Efficiencies of the Bates PMTs Measurements done by Y. Illieva For comparison PMTs Quantum Efficiency at the same gain G (all PMTs HV was set for the gain 2 10 7 ) and at fixed LED intensity (I=const) we have measured the number of detected photoelectrons : In this case Npe ~ G I QE ~QE (since G I = const and same for all PMTs) Distribution of Npe detected by PMTs XP4500 at the same gain and same light intensity. Wide spread in Npe reflect spread in Quantum Efficiency of PMTs from the MIT Bates 6
Magnetic Field Effect on PMT The Earth magnetic field effect on PMT without and with shield have been studied when PMT axis is in horizontal plane and oriented along or perpendicular to the field. (Data from L. Zurmbonwi & H. Mkrtchyan) Without magnetic shield field effect strongly depends on the azimuthal angle of the PMT With shield even when PMT photocathode is 4cm out from the shield the field effect is very small Light collection and magnetic shield efficiency have been studied versus Photocathode depth in shield. Simulations show that moving the PMT windows fully inside the mu-metal cylinder reduce signal by ~15%. This effect can be minimized to ~5%, if the cylinder will be covered with Mylar from inside. Magnetic shield already is effective when PMT is in or out from the mu-metal cylinder within ±3 cm. Magnetic field can: a) Decrease the efficiency of p.e. collection, when a part of the p.e. created at the photocathode are deviated from nominal trajectory and do not reach the first dynode. b) Decrease the gain of the PMT, when fraction of secondary electrons from one dynode deviates from nominal trajectory and does not reach the next dynode. 7
Coordinate & Npe dependencies with 6 top PMTs Simulations done by S. Zhamkochyan Simulation for coordinate dependencies & Npe with additional 6 top PMTs. Primary particles are generated according to the SHMS optics with Pmean = 3GeV. Top plots SP30 aerogel, Bottom plots SP15 aerogel. With additional top 6 PMTs ~20% more Npe is expected, but with strong Y coordinate non-uniformity. 8
Mylar or Millipore Simulations done by S. Zhamkochyan Prototype switching of reflective material for test Millipore Mylar NPE vs aerogel thickness dependences for specular (Mylar is considered) and diffuse (Millipore) wrappings. Primary particles are 3 GeV π -, falling transversely on the detectors center. 9
SUMMARY Revision and testing of Bates PMTs XP4500B, Aerogels(SP-30 & SP-20) and Bases Built two prototypes for cosmic and aerogel tests Monte-Carlo studies have been done, Yield Npe ~14 is expected with SP-30/10cm SP-15 arrived (test batch), one of diffusion boxes and 3 trays are ready Measured and tested all mechanical parts dimensions Magnetic shielding tests, isolation of PMT from surrounding metal (HV), light-leak tests GEANT4 simulations and tests of reflectors, decision for reflective material (ESR & Millipore) Updates in Wiki and elogs: http://www.vsl.cua.edu/cua_phy/index.php/mainpage:nuclear:kaondetector https://hallcweb.jlab.org/elogs/yerevan Upcoming Aerogel prototype tests for low index, signal dependence on aerogel thickness Test of lowest index aerogel sample: refractive index, light transmittance Select ion of PMTs with highest and close QE to provide uniformity of the detector over surface Full Assembling of diffusion box with reflector and aerogel Development of the strategy for electronics. Start full scale cosmic tests Work on aerogel software (calibration and analysis code). 10
Detector Hut Super High Momentum Spectrometer Calorimeter Calorimeter is situated at the very end of SHMS detector stack With effective area 120cm x 140cm, it will cover SHMS acceptance Higher energy leads to thicker calorimeter than in HMS/SOS Energy resolution better than 7% (at 1 GeV energy) is expected π/e rejection 200:1 with Preshower & Shower (at 99.5% e efficiency) Preshower consists of 28 modules (TF-1) from the SOS calorimeter stacked back to back Shower part consists of 224 modules (F-101) from decommissioned HERMES detector 11
Shower current & planned setup Simulations done by T. Horn Revision and testing of Hermes blocks Refurbished damaged modules (light leaks, glued broken,) Tested for radiation damage, transmittance and healing Each block has been under cosmic test PMTs tested for gain & sep at optimal HV Monte-Carlo studies done Best 224 (+8 ) available are selected & ready for installation. 12
Preshower current stage Revision and testing of 28 blocks & PMTs from SOS Lead Glass tested for transmittance and radiation damage PMTs tested for gain & sep at optimal HV Blocks wrapped in Mylar & Tedlar and installed Refreshed few scintillators from SOS for cosmic test Monte-Carlo studies have been done All blocks and PMTs installed in the assembly Electronic setup and currently running cosmic tests Prototype was build for optical coupling test Tested for best optical contact, chosen grease 13
SHMS Preshower Cosmic Test Preshower electronic setup running cosmic test Thanks to Mark Jones, Brad Sawatzky, Ed Brash and Jordan Cardenas 14
GEANT4 Simulation for cosmic test Simulations done by S. Zhamkochyan Npe histograms, Monte-Carlo for currently running cosmic setup 15
Cosmic test result Npe histograms for 14 blocks of Preshower located on Positive side, P2 & P14 are triggers. 16
SHMS Preshower Cosmic test (raw data) Using top/bottom scintillator triggers setup parallel to preshower blocks. HV setting on all 14 blocks is 1.7 KV, ADC input jumper setting 1V, ADC_DAC level 3300. Pedestals are subtracted. All 14 channels are active and getting signals. Some difference due to different gains and air optical contact. 17
SHMS Preshower Cosmic test, 3 setup compared From top to bottom: - 1 st pair, HV is 1700 V, triggers set cross top, cross bottom' at PMTs closest point, - 2nd pair, same setup but HV set for similar gain using gain vrs HV data, - 3rd pair, same HV as for 2 nd case, but triggers at farthest point from PMTs. 1P(1620V) 3P(1700V) 5P(1730V) 7P(1760V) 9P(1760V) 11P(1800V) 13P(1830V) 2P(1660V) 4P(1720V) 6P(1750V) 8P(1730V) 10P(1780V) 12P(1830V) 14P(1870V) 18
SUMMARY Shower blocks are fully tested and ready for installation Preshower part is assembled and currently under cosmic test Monte-Carlo studies have been done π/e rejection 200:1 with Preshower &Shower (at 99.5% e efficiency) is expected. Running cosmic test on Preshower Upcoming Development of the strategy of calorimeter electronics. Crosstalk test between adjacent Preshower blocks. Work on calorimeter software (calibration and analysis code). 19