1/41 LXe Beam Test Result CEX beam test 2004 Cryogenic Equipment Preparation Status Liquid Xenon Photon Detector Group

2 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

3 1 st generation R6041Q2 nd generation R9288TB3 rd generation R9288ZA 228 in the LP (2003 CEX and TERAS) 127 in the LP (2004 CEX) 111 In the LP (2004 CEX)Not used yet in the LP Rb-Sc-Sb Mn layer to keep surface resistance at low temp. K-Sc-Sb Al strip to fit with the dynode pattern to keep surface resistance at low temp. K-Sc-Sb Al strip density is doubled. 4% loss of the effective area. 1 st compact version QE~4-6% Under high rate background, PMT output reduced by % with a time constant of order of 10min. Higher QE ~12-14% Good performance in high rate BG Still slight reduction of output in very high BG Higher QE~12-14% Much better performance in very high BG PMT Development Summary

4 Alpha sources on wires 4 tungsten wires plated with Au (50 micron  ) 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 ( Å) Fixed on the wall with spring. Alpha sources on the walls were removed gamma wire LED

5 New Refrigerator (PC150W) MEG 1 st spin-off Technology transferred to a manufacturer, Iwatani Co. Ltd Performance obtained at Iwatani  189  6.7 kW compressor  4 Hz operation

6 CEX Elementary process  - p   0 n  0 (28MeV/c)    MeV  eV Requiring   FWHM = 1.3 MeV Requiring  > 175 o FWHM = 0.3 MeV   170 o 175 o 00     54.9MeV82.9MeV 1.3MeV for  >170 o 0.3MeV for  >175 o

7 Beam Test Setup H 2 target+degrader beam LP NaI LYSO Eff ~14% S1 Eff(S1xLP)~88%

8 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 x10 8 п - /sec  Slits 100: 3.95 x10 8 п - /sec Profile at S1, 2mm/bin Optimization of degrader thickness 20mm + 3.3mm x n

9 Operation Status Thanks to a new refrigerator we 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

10 Data set GainADC gateBeam intensityevent# * High 400 nsec Low- middle ** k high- 600 nsec low- middle48 k high- Normal 400 nsec low55 k middle ** k high- 600 nsec low77 k middle85 k high47 k And Waveform data…

11/41 Analysis Result Calibration Energy Timing 1 st look on waveform Data

12 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 Wire (50 μm ϕ ) Alpha 40 μm Po half-life=138 days

13 The two wires on the front face are a little displaced LXeGXe Source Position Reconstruction

14 Alpha data analysis Nphe[0] Nphe[0] for top-left alpha Center of the PMT-0 with alpha emission angle selection

15 LXe/MC, absorption length evaluation Applying the QEs determined in GXe (-75˚C) 4 front sources

16 Q.E. evaluation with alpha events in liquid R9288 R6041 Data #8528 normal gain front 4 alphas MC reflection on quartz on no absorption scattering length :45cm for 175 nm Q.E. evaluation using alpha data in the liquid is also possible. Higher light yield  Expected better evaluation if xenon is pure!

17/41 Energy Reconstruction Cut-based Qsum Analysis Linear Fit Analysis

18 Cut-based Qsum analysis Event Selection 83 MeV to Xe 55 MeV to Xe Cut-based Qsum analysis MC E xenon [n ph ] Analyze only central events to compare with the previous result  |X rec |, |Y rec |<2cm  70 MeV < E NaI +E LYSO < 105MeV  Sigma2 > 40 (discard events if shallow) Sigma2: broadness of the event measured by using front face PMTs  depth parameter

19 Correction and selection efficiency Before depth correction After depth correction with a linear function Cut-based Qsum analysis 83MeV 55MeV # of events In 55 MeV peak no cut260k15k 55 MeV selection with the other gamma 55k8129 position selection depth selection %

20 Energy Resolution  = 1.23 ±0.09 % FWHM=4.8 % 55 MeV σ = 1.00±0.08 % FWHM=5.2% 83 MeV Cut-based Qsum analysis  =1.53% FWHM = 4.5 ± 0.3  =1.16 ± 0.06% FWHM = 5.0 ± 0.6 CEX 2003 CEX 2004

21 Linear Fit analysis 55 MeV event selection Correlation with NaI/Lyso 83 MeV in LXe 55 MeV in LXe Y (cm) X (cm) Small displacement (~ 0.5 cm) Linear Fit analysis In general it is possible to obtain higher efficiency with the linear fit analysis In general it is possible to obtain higher efficiency with the linear fit analysis

22 Energy (Linear Fit) and Qsum reconstruction 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. No selection, 600k events NaI cut, 144k events NaI+sat cut, 83k events NaI+sat+coll cut, 54k events NaI cut: 70 MeV  QNAI  100 MeV Coll. cut: (X 2 + Y 2 ) 1/2  4.75 cm Linear Fit analysis

23 Energy vs. Depth Correction along X & Y E (MeV) Z (cm) Red: all events; Green: no saturated Remove ADC saturated events is equivalent to a depth cut. Linear Fit analysis We observed a slight position dependence of the reconstructed Energy. It can be corrected by using a parabolic interpolation. E (MeV) No Need Anymore

24 Saturation & NaI cut + R<1.5 cm FWHM = 4.8 % Reconstructed Energy (updated) Correction (X&Y) effect  0.3 % Linear Fit analysis 83MeV Saturation & NaI cut FWHM = 5.6 % 55MeV

25 Position dependence of energy resolution

26/41 Timing Analysis Intrinsic, L-R analysis Absolute, Xe-LYSO

27 T = TDC - Tref TDC correction for time-walk and position And correction for position T L, T R by weighted average of T i = (T L  T R )/2 The algorithm  i =r.m.s. of T i cut on Q i > 50 pe Left Right  LP NaI  S1 LYSO t LP - t LYSO --  TLTL TRTR

28 Intrinsic resolution, L-R analysis Position and T ref corrections applied Applied cuts: |x|< 5cm, |y|<5cm E LYSO +E NaI >20 MeV RF bunch and TDC sat. Study of  vs N pe  = pe  = 39 pe QE still to be applied Old data New data L-R analysis

29 Absolute resolution, Time reference (LYSO) LYSO PMT1 & 2 Coorected for x-coord. (not for y) Corrections applied for time walk (negligible at high energy deposit) PMT1 PMT2 Xe- LYSO analysis LYSO gamma slit (T LYSO(R) -T LYSO(L) )/2 with 1cm slit  =64 psec

30 Absolute timing, Xe-LYSO analysis 55 MeV high gain normal gain 110 psec 103 psec Xe- LYSO analysis  LYSO Beam L-R depth reso = 65 = psec = 53 = psec Normal gain High gain

31/41 1 st look on the waveform data

32 DRS Setup 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 LP Front Face DRS0DRS1 Xe(  ) DRS inputs LP: central 12 PMTs LYSO: 2 anode signals for each DRS chip as time reference DRS chip calibration Spike structure left even after calibration, which will be fixed by re- programming FPGA on the board.

33 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)/τ rise ) 2 )- exp(-((t-t0)/τ decay ) 2 ))  CR-RCn shaping V(t)=A((t-t0)/τ decay ) n exp(-(t-t0)/τ decay )  Averaged waveform template Xenon τ rise =7.0nsec τ decay =35nsec

34  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. α γ Pulse height [mV] Time constant Pulse shape discrimination LYSO time resolution

35 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 -40mV -160mV -1200mV

36 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=+30nsecΔT=+60nsec

37 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 ΔT=-15nsec ΔT=-10nsecΔT=-5nsec ΔT=+15nsec Original Differential easy Difficult but not impossible ? easy

38/41 Cryogenic Equipment Preparation Status

39 PC150W performance Condition:  6.7kW(60Hz) 4Hz Twater=20 C (Iwatani )  6.0kW(50Hz) 4Hz Twater>30 C (PSI ) New PT(190W) and KEK original (65W) at PSI at Iwatani Calorimeter operation without LN2 at PSI(Sep.to Oct.2004) 42-day operation without degradation in cooling performance

40 Current status/schedule of liquid-phase purification test xenon Liquid pump Purifier cartridge LP top flange 17/Jan wire installation & closing the cryostat 24/Jan setup in PiE5 -13/Feb evacuation 7-20/Feb liq. N 2 piping 14/Feb-13/Mar liquefaction and test 14/Mar recovery New calibration wires with higher intensity 9MeV gamma from Nickel

41/41 End of Slide

42 The algorithm TDC correction for time-walk and position (point-like approx) vertex reco. by weighted average of PMTs (new QE set, see Fabrizio Cei’s talk) T L, T R by weighted average of T i = (T L  T R )/2  i =r.m.s. of T i cut on Q i > 50 pe

43 The algorithm T9F20  = (290  5) ps  = (345  5) ps  Side PMTs are less sensitive to z-fluctuations than Front PMTs

44 T LXe - T LYSO Global non-linear corrections for  -vertex (  50 ps) mainly due to: scale compression (operated by PMT average) finite shower size

45 Beam spot on target Beam profile  H = 13.2 mm  V = 9.9 mm (as measured by Peter)     62.3 ps