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## LXe Beam Test Result

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**LXe Beam Test Result**CEX beam test 2004 Cryogenic Equipment Preparation Status Liquid Xenon Photon Detector Group**Charge Exchange Beam Test at piE5**• New PMTs R9288TB • higher QE and better performance under high BG • Resolutions to be improved • New calibration alpha sources • New refrigerator with higher cooling power • TEST at piE5 beam line • Gain experience • Analysis framework • ROME in online (offline also) analyses • Waveform data obtained with DRS prototype boards**Alpha sources on wires**• 4 tungsten wires plated with Au (50 micron f) • Po attached on the wires, 2 active points per wire • ~40Bq per point on 2 wires at the rear side • ~130Bq per point on 2 wires at the front side • Active points are coated with Au (200-400Å) • Fixed on the wall with spring. • Alpha sources on the walls were removed wire LED gamma**New Refrigerator (PC150W)**• MEG 1st spin-off • Technology transferred to a manufacturer, Iwatani Co. Ltd • Performance obtained at Iwatani • 189 W @165K • 6.7 kW compressor • 4 Hz operation**Eg**170o q Eg Eg p0 175o q 54.9MeV 82.9MeV 1.3MeV for q>170o 0.3MeV for q>175o Eg CEX Elementary process • p-pp0n • p0(28MeV/c) g g • 54.9 MeV < E(g) < 82.9 MeV • Requiring q>170o • FWHM = 1.3 MeV • Requiring q > 175o • FWHM = 0.3 MeV**Beam Test Setup**H2 target+degrader LYSO Eff ~14% NaI LP S1 Eff(S1xLP)~88% beam**Beam Condition**• Profile at the target (with a pill counter) • Vertical 13.2mm • Horizontal 9.9mm • Pion rates (w/o separator) 1.8mA and 4cm Target E. • Slits 80: 2.07 x108п-/sec • Slits 100: 3.95 x108 п - /sec Optimization of degrader thickness 20mm + 3.3mm x n Profile at S1, 2mm/bin**Operation Status**• Thanks to a new refrigeratorwe succeeded to operate the detector (almost) without using LN2 except for power break and recovery. • New pressure reducer also helped this while pre-cooling and liquefaction. • Circulation/purification continued during DAQ. • History • September • 18~21 Pre-cooling (72 hrs) • 21~24 Liquefaction (79 hrs) • 24 Circulation start (~30 cc/min) • 24 Electronics setup • October • DAQ started • 25 DRS boards installed • 29 Recovery of xenon**Data set**• And Waveform data…**Analysis Result**Calibration Energy Timing 1st look on waveform Data**Wire (50 μm ϕ)**Alpha 40 μm Alpha data • One of the rear wires found to be slipped • Weighted position average surround wires due to shadow effect. Reconstructed Position is far from wires Po half-life=138 days**Source Position Reconstruction**• The two wires on the front face are a little displaced LXe GXe**Alpha data analysis**Nphe[0] Nphe[0] for top-left alpha with alpha emission angle selection Center of the PMT-0**LXe/MC, absorption length evaluation**4 front sources Applying the QEs determined in GXe (-75˚C)**Q.E. evaluation with alpha events in liquid**Q.E. evaluation using alpha data in the liquid is also possible. Higher light yield Expected better evaluation if xenon is pure! R9288 R6041 Data #8528 normal gain front 4 alphas MC reflection on quartz on no absorption scattering length :45cm for 175 nm**Energy Reconstruction**Cut-based Qsum Analysis Linear Fit Analysis**Analyze only central events to compare with the previous**result |Xrec|, |Yrec|<2cm 70 MeV < ENaI+ELYSO < 105MeV Sigma2 > 40 (discard events if shallow) Sigma2: broadness of the event measured by using front face PMTs depth parameter Cut-based Qsum analysis Cut-based Qsum analysisEvent Selection 83 MeV to Xe 55 MeV to Xe Exenon[nph] MC**Cut-based Qsum analysis**Correction and selection efficiency 83MeV 55MeV Before depth correction 78 % After depth correction with a linear function**Cut-based Qsum analysis**Energy Resolution CEX 2004 CEX 2003 55 MeV s=1.53% FWHM = 4.5 ± 0.3 • = 1.23 ±0.09 % FWHM=4.8 % 83 MeV s=1.16 ± 0.06% FWHM = 5.0 ± 0.6 σ= 1.00±0.08 % FWHM=5.2%**In general it is possible to obtain higher efficiency with**the linear fit analysis Linear Fit analysis Linear Fit analysis55 MeV event selection Y (cm) Correlation with NaI/Lyso 83 MeV in LXe 55 MeV in LXe X (cm) Small displacement (~ 0.5 cm)**Linear Fit analysis**Energy (Linear Fit) and Qsum reconstruction No selection, 600k events NaI cut, 144k events Black: Linear Fit Red: QSUM Linear Fit trained using MC including Fresnel reflection; used Q.E. determined with six sources. No large differences changing Q.E. set. The Linear Fit works better. NaI+sat cut, 83k events NaI+sat+coll cut, 54k events NaI cut: 70 MeV<QNAI<100 MeV Coll. cut: (X2 + Y2)1/2< 4.75 cm**Linear Fit analysis**Energy vs. DepthCorrection along X & Y E (MeV) E (MeV) E (MeV) No Need Anymore Red: all events; Green: no saturated We observed a slight position dependence of the reconstructed Energy. It can be corrected by using a parabolic interpolation. Z (cm) Remove ADC saturated events is equivalent to a depth cut.**Linear Fit analysis**Reconstructed Energy (updated) 83MeV 55MeV Saturation & NaI cut FWHM = 5.6 % Saturation & NaI cut + R<1.5 cm FWHM = 4.8 % Correction (X&Y) effect 0.3 %**Timing Analysis**Intrinsic, L-R analysis Absolute, Xe-LYSO**NaI**g S1 g LP LYSO tLP - tLYSO The algorithm p- • T = TDC - Tref • TDC correction for time-walk and position • And correction for position • TL, TR by weighted average of Ti • <T> = (TLTR)/2 TL i=r.m.s. of Ti cut on Qi> 50 pe Left Right g TR**L-R analysis**Intrinsic resolution, L-R analysis • Position and Tref corrections applied • Applied cuts: • |x|< 5cm,|y|<5cm • ELYSO+ENaI >20 MeV • RF bunch and TDC sat. • Study ofsvs Npe • s= 65 ps @ 35000 pe • s= 39 ps @100000 pe • QE still to be applied Old data New data**LYSO PMT1 & 2**Coorected for x-coord. (not for y) Corrections applied fortime walk (negligible at high energy deposit) LYSO slit slit gamma Xe- LYSO analysis Absolute resolution, Time reference (LYSO) (TLYSO(R) -TLYSO(L))/2 s=64 psec PMT1 PMT2 with 1cm slit**Xe- LYSO analysis**Absolute timing, Xe-LYSO analysis high gain normal gain 103 psec 110 psec 55 MeV Normal gain High gain**LP Front Face**DRS0 DRS1 DRS Setup • DRS inputs • LP: central 12 PMTs • LYSO: 2 anode signals for each DRS chip as time reference • Two DRS chips were available. • 10ch/chip (8 for data and 2 for calibration) in total 16 for data • 2.5GHz sampling (400ps/sample) • 1024 sampling cells • Readout 40MHz 12bit • Free running domino wave stopped by trigger from LP • DRS chip calibration • Spike structure left even after calibration, which will be fixed by re-programming FPGA on the board. Xe(g)**Simple Waveform Fitting**• Simple function with exponential rise and decay can be nicely fitted to the xenon waveform. (and also LYSO waveform) • Other Fitting functions • Gaussian tail • V(t)=A(exp(-((t-t0)/τrise)2)-exp(-((t-t0)/τdecay)2)) • CR-RCn shaping • V(t)=A((t-t0)/τdecay)n exp(-(t-t0)/τdecay) • Averaged waveform • template τrise=7.0nsec τdecay=35nsec Xenon**Time constant**γ α Pulse height [mV] a/g separation & LYSO timing • Alpha events are clearly discriminated from gamma events. • This does not highly depend on the fitting procedure. • LYSO time resolution is similar to that obtained with TDC. Pulse shape discrimination LYSO time resolution**Averaged Waveform**• An averaged waveform can be used • for fitting as a template • for simulating pileup • for testing analysis algorithm etc. • The measured waveforms are averaged after synchronizing them with T0 • Use the “template” for fitting! • Pulse shape seems to be fairly constant for the gamma event. Average -160mV -1200mV -40mV**Simulation of Pileup Events**• Overlapping pulses are simulated using averaged waveform to test rejection algorithm. • Real baseline data obtained by the DRSs is used. Npe1=2000phe Npe2=1000phe (3000phe is typical for 50MeV gamma) ΔT=+30nsec ΔT=+60nsec ΔT=-30nsec**Trial of Pileup Rejection**• It seems easy to break up overlapping pulses >10ns apart from each other. • Rejection power is being investigated for different sets of (Npe1, Npe2) and ΔT. Npe1=2000phe Npe2=1000phe Original ΔT=-10nsec ΔT=-5nsec ΔT=-15nsec ΔT=+15nsec Differential ? easy easy Difficult but not impossible**PC150W performance**at Iwatani • Condition: • 6.7kW(60Hz) 4Hz Twater=20 C (Iwatani 2003.12) • 6.0kW(50Hz) 4Hz Twater>30 C (PSI 2004.7) at PSI New PT(190W) and KEK original (65W) Calorimeter operation without LN2 at PSI(Sep.to Oct.2004) 42-day operation without degradation in cooling performance**17/Jan wire installation & closing the cryostat**24/Jan setup in PiE5 -13/Feb evacuation 7-20/Feb liq. N2 piping 14/Feb-13/Mar liquefaction and test 14/Mar recovery Current status/schedule of liquid-phase purification test Purifier cartridge Liquid pump • New calibration wires with higher intensity • 9MeV gamma from Nickel LP top flange xenon**The algorithm**• TDC correctionfor time-walk and position (point-like approx) vertex reco. by weighted average of PMTs (new QE set, see Fabrizio Cei’s talk) • TL, TRby weighted average of Ti • <T> = (TLTR)/2 i=r.m.s. of Ti cut on Qi> 50 pe**The algorithm**T9 F20 s = (2905) ps s = (345 5) ps Side PMTs are less sensitive to z-fluctuations than Front PMTs**TLXe - TLYSO**• Global non-linear corrections for g-vertex (50 ps) • mainly due to: • scale compression (operated by PMT average) • finite shower size**Beam spot on target**• Beam profile • sH = 13.2 mm • sV = 9.9 mm • (as measured by Peter) • sp = 62.3 ps