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Autonomous Rate Measuring System

Autonomous Rate Measuring System. Theodoros Athanasopoulos Representing the KM3NeT Consortium Nestor Institute For Astroparticle Physics VLV v T09 Athens 13 th – 15 th October 2009. Autonomous Rate Measuring System. Target of the experiment

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Autonomous Rate Measuring System

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  1. Autonomous Rate Measuring System Theodoros Athanasopoulos Representing the KM3NeT Consortium Nestor Institute For Astroparticle Physics VLVvT09 Athens 13th – 15th October 2009 VLVvT09 Theodoros Athanasopoulos

  2. Autonomous Rate Measuring System • Target of the experiment To measure the effect of sedimentation and bio-fouling on the glass surface of optical modules deployed in the deep sea. • How do we measure? We will periodically measure and record the singles at ½ spe and doubles (in a 10ns window) PMT rates caused mainly by K40 decays and monitor the gain by recoding the single photoelectron pulse height. VLVnT09 Theodoros Athanasopoulos

  3. Autonomous Rate Measuring System An Autonomous System The PMT Rate Measuring System is an autonomous system, battery powered, designed to operate for more than 1 year with data recorded in memory and monthly transfers acoustically to surface. Due to limited battery life of the acoustic modem, data transmitted has been designed to be only 40kB per month. Battery life is also an issue for the rest of the electronics so low power electronics have been designed and developed for this system. The system will be in sleep mode most of the time. It will turn on only for 1 hour every week to take the measurement, store the data and go to sleep mode again. It will also wake up to transmit the data upon acoustical request. System total power consumption is: On Mode: 40W => 40W x 52h = 2080Wh Total power consumption = 3219Wh Off Mode: 130mW => 130 x 8760h = 1139Wh Total power supplied = 8400Wh Use of alkaline batteries VLVnT09 Theodoros Athanasopoulos

  4. System Description (Mechanical) APPARATUS LAYOUT (Side View) 8 Optical Modules (4 pairs) Battery bank x 4 VLVnT09 Theodoros Athanasopoulos

  5. Acoustic Modem OM1 Board to FPGA buses SD 1GB 4 Channel Discriminator MAX964 OM2 4 Channel ADC AD7476 System Description (Electronics) FPGA Spartan 3E OM3 14bit bus μController PIC18F4550 OM4 4 Channel Discriminator MAX964 OM5 4 Channel ADC AD7476 8ch HV Control Slow Controls OM6 8ch HV Monitor Power Regulation & Power Distribution System OM7 OM8 VLVnT09 Theodoros Athanasopoulos

  6. Assembled System FPGA Board Power Regulation and Power Distribution Unit VLVnT09 Theodoros Athanasopoulos

  7. Front End Electronics From Other Discriminators Coincidence Logic Inverted and amplified PMT Pulse To Doubles Rate Counter Discriminator Pulse Discriminator ½ SPE AMP To Singles Rate Counter PMT Pulse Peak and Hold ADC VLVnT09 Theodoros Athanasopoulos

  8. Conclusion We have designed a low power autonomous system to measure the K40 rate to stay in the sea for more than one year. It will be sensitive to reductions in the singles and doubles rate at single photoelectron conditions due to sediment adhesion. Data will be retrieved periodically acoustically. Expected deployment end of this month. System is currently being tested at the Nestor Lab. VLVnT09 Theodoros Athanasopoulos

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