Test Results from Quality Control Measurements of Phototubes for the CMS-CASTOR Calorimeter

1. Test Results from Quality Control Measurements of Phototubes for the CMS-CASTOR Calorimeter Presented by* S. Aydın1, I. Dumanoglu1, G. Onengut1, S. Ozturk1 and K. Sogut2 1 University of Cukurova, Department of Physics, Adana, TURKEY. 2 University of Mersin, Department of Physics, Mersin, TURKEY. 11th Vienna Conference on Instrumentation, Vienna, Feb 19-24, 2007. Hamamatsu R5380 Phototubes The CMS-CASTOR Detector Phototube Specifications In the CASTOR calorimeter hadronic and photonic contents of the interactions will be determined by the detection of the Cherenkov light. Cherenkov light produced in the quartz plates will be read by PMTs. It is transmitted to the phototubes through the aircore light guides. • The very forward region of the CMS will be completed by the ZDC and CASTOR calorimeters. • They will locate after the HF detector and cover almost the whole angular region. • CASTOR will investigate the baryon rich very forward rapidity range (5.2 to 6.6) of central • Pb+Pb collisions @ 5.5 TeV. • The physics goal of the calorimeter is to study the anomalistic events called centauros and • stranglets. Such events have been detected in the earlier cosmic ray experiments. • CASTOR will locate at 14.36 m from the interaction point. It surrounds the beam pipe azimuthally • and is divided into 16 sectors. Longitudinally it consists of 18 successive layers that are made of • tungsten plates. Tungsten plates are followed by the quartz plates. Schematic view of PMT. Calorimeter will be equipped with 224 Hamamatsu R5380 phototubes (PMT). The testing systems for measuring the gain and timing parameters Gain Testing System System to measure the timing parameters • We used a 337 nm pulsed laser source for measuring the timing • parameters. • Laser ray passes an NDF and then hits a beam splitter. The • reflected light is directed to a PIN diode and the transmitted light • is sent to PMT after passing through few more NDFs. • PIN diode that was powered with 7 V was used to trigger the oscilloscope. • PMT signal was evaluated with a LeCroy oscilloscope that has an • OS itself. • Rise time, pulse width and transit time values of each PMT are • measured. • Gain measurements are done in the light-tight boxes. • A 12 V, 20 W halogen lamp is used as the light source. • Light comes to PMT through a Neutral Density Filter (NDF, factor=2). • Currents for gain measurement are read by a picoammeter. • Light intensity inside the box is monitored by a spectrometer to make • sure the stability of the measurements each time. • All the gain measurements are performed with a high voltage supply • that was to range from 500 V to 1600 V with a 50 V step at each • measurement. • Data acquisition is done with a LabView code. Schematic view of timing setup Screenshot of oscilloscope Results of the measurements 3. Timing Parameters 2. Anode Dark Currents Preferred Values of Parameters Number of PMTs Number of PMTs Pulse Width (ns) Transit Time (ns) 1. Gain Measurements PMT Gain = Anode Current / Cathode Current Measured Value : 5831 @ 1100 V Conclusion • We measured dark currents, gains and timing • parameters of 34 PMTs. • All the measured timing parameters were below • the requirements of the CASTOR Group. • The average PMT gain is around 6000 which is • acceptable during the operation of CASTOR. • All the dark current measurements were also • in the acceptable range. Number of PMTs Number of PMTs Rise Time (ns) Gain