Photodetector Testing Facilities at Nevis Labs & Barnard College. Reshmi Mukherjee Barnard College, Columbia University

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1 Photodetector Testing Facilities at Nevis Labs & Barnard College Reshmi Mukherjee Barnard College, Columbia University First AGIS Collaboration Meeting, UCLA, June 26-27, 2008

2 M64 MAPMT Testing for Double Chooz Outer Veto Columbia University (Leslie Camilleri, Janet Conrad, Camillo Mariani, Mike Shaevitz, Graduate students: Arthur Franke & Matt Toups, Electronics: Jaro Ban, Bill Sippach) Barnard College (Reshmi Mukherjee, student: Camille Avestruz) Role of Barnard in NSF proposal: In collaboration with Columbia, Barnard has the responsibility for testing the M64 MAPMTs. Test noise level of each pixel, measure gain and crosstalk between channels. Dark room at Barnard. Testing of the photo-detectors will be carried out on campus by Barnard and Columbia undergraduates during the semester and in the summer. Undergraduate participation in calibration and analysis. Onsite laboratory access for Barnard students. Hands-on hardware experience for Barnard Physics majors.

3 Maroc 2 studies Ongoing MAPMT tests ADC response Pre-amplifier linearity study Cross Talk Study PMT board M64 Baseline stability as a function of Time HV value Pulse height as a function of : HV value; Light intensity. Pre-calibration procedure Gain study at 1PE and 10PE level Noise rate per pixel as a function of HV

4 M64 Multi-anode PMT Testing and Readout Electronics Each M64 Pixel: ADC Readout Disc. Readout H8804 M64 MAROC2 Chip

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7 PMT Characterization Goal: Fully illuminate each M64 with an amount of light that is nominally what we expect to receive at the experiment (~10 PE) Use internal settings of the chips to equalize response of each pixel

8 Maroc 2 Chip studies ADC response Picoquant light source Picoquant light source PMT PMT Digital oscilloscope ADC fc/adc Conversion The PicoQuant light source consists of a pulsed laser driver and an interchangeable LED head. Light pulse widths are ~1 ns fc/adc 10 PE Onset of ADC saturation well above expected signal Matt Toup

9 PMT Characterization After HV adjustment Spread = 20% After Pixel pre-amp Adjustment Spread = 2% NSF REU - Sophie Berkman

10 M64 studies gain measurements Naïve photon statistics gives: Q = N! Q = pe ge N pe ge e = electron charge g = Gain N pe = Number of photoelectrons Q = charge A more rigorous calculation gives the following: N 1 g 2 Q pe =! + " 2 Q Q = "! 1 2 Q ( 1 w 2 ) 2 ( + w )! e w = width of single - pe peak Matt Toups

11 M64 studies gain measurements, SPE 1 pe ~ 40 ADC Fit to the single-pe distribution [adapted from MINOS article NIM A (2005) ] A& N events e P( x y) = N entries 6 20 $ ( q$ q ped $ mge/ " ) 1 2 2! P( n N pe) % P( m n" ) e n= 0 m= 0 2#! &% y x!! y A = Normalization factor N pe x = Number of = Number of entries photoelectrons ( g 2 = ( 2 ped = Gain 2 m & ge # + $! ' % ' " e = electron charge! = Secondary emission ratio 2 The 6 fit parameters are : A, N, g, ",!, q pe ped ped Matt Toups

12 Fractional difference between SPE and Gauss fits M64 studies gain measurements, summary PMT SPE (10 5 ) Gauss (10 5 ) Asymmetry (%) Hamamatsu (10 5 ) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± The result of our two fits agree well, but we they are higher (»40%) higher with respect to the measurement reported by Hamamatsu. We have to remember that we are measuring something like: ! anode luminosityi cathode luminosity i= 1 i Whereas Hamamatsu instead measures: 64! i= 1 64! i= 1 anode luminosity cathode luminosity i i

13 M64 studies noise rates, summary PMT Noise rate (Hz/pixel) with DAC=1/3 PE Noise rate (Hz/pixel) with DAC=2/3 PE Noise rate (Hz/pixel) with DAC=1 PE Noise rate (Hz/pixel) with DAC=2 PE Dark current Hamamatsu (na) Note: This data taken at 800V for all tubes

14 Phototube Alignment & Testing Precison screw to move mask Large Dark box Picoquant source window in box tube moveable mask Light ws block alignment block attached to tube ~ 2 m, so light is even across faces pins for the alignment Large dark box is never opened. Tube attaches at window on outside.

15 Alignment system for MAPMTs Alignment system used to drill the precision holes in the phototubes. The tube is moved using the precision stage at the bottom left until the alignment marks on the tube line up with fiducial marks. The tube is then bolted in place and holes are drilled using precision drill bushings in the top plate.

16 Plans for AGIS M-16 Test Setup Use/modify existing M-64 setup at Barnard/Nevis. Test M16 on loan from Hamamatsu Modify PMT board. Explore other readout schemes. Take advantage of Nevis infra-structure and support Use existing DAQ readout, software. Dark room at Barnard. Characterize MAPMTs. Test noise level of each pixel, measure gain and crosstalk between channels.

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18 Pulse Diode Laser Fastest miniature sub-nanosecond pulsed UV/blue/green/orange LED sources available Short laser pulses down to 50 ps (FWHM) High repetition rates from single shot to 40 MHz (optional 64 or 80 MHz) Laser heads with wavelengths from 375 nm to 1550 nm LED heads with wavelengths from 260 nm to 600 nm External trigger / Sync Output