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CosmicSatCosmicSatCosmicSatCosmicSat
University of Northern ColoradoUniversity of Northern Colorado
April 2, 2004April 2, 2004
CosmicSat Goals Objective:
Determine charged particle count with altitude using a coincidence count detector
NASA Benefits: Measure cosmic radiation in a Mars-like atmosphere using a small detector
CosmicSat System Requirements:
Detectors , coincidence counts circuit, housing, heating circuit and data storage.
Payload mass - ~ 2 kg Atmospheric temperatures of ~ - 60 degrees F Large atmospheric pressure differential
Coronal Discharge Magnetic shielding Crash survival
CosmicSat: System Overview
Scintillator
PMTPMT
Scintillator
Coincidence Circuit
Data Logger Batteries
BatteriesHeaterCircuit
Switches
Subsystem: PMTs and Scintillator Purpose:
Scintillator: Interacts with charged particles Excites electrons between molecular bound states Electron de-exitation produces photons Photon travels along scintillator undergoing many total internal reflections
Photomultiplier Tubes: Collect photons Converts photons to an electronic signal
PMTs and ScintillatorPMTs and Scintillator Photomultiplier Tube
Module Interfaces:
Base encased with PMT High voltage source in
base Requires an external 5V
power source Base interfaced with
coincidence count circuit
Optical grease between PMT face and scintillator
Base PMT Head
PMTs and Scintillator
The PMTs bonded to The PMTs bonded to scintillatorscintillator
Organic Scintillator Organic Scintillator wrapped in Mylar foil wrapped in Mylar foil and electrical tapeand electrical tape
PMTs wired to PMTs wired to coincidence circuit via coincidence circuit via BNCsBNCs
Scintillator
PMTPMT
Scintillator
Charged Particles
OpticalGrease
VacuumEpoxy
PMTs and ScintillatorPMTs and Scintillator
Housing:Housing: PMTs encased in PVC PMTs encased in PVC
pipe – maintain pipe – maintain atmospheric pressureatmospheric pressure
PMT – scintillator joined PMT – scintillator joined with vacuum epoxy and with vacuum epoxy and then JB Weld. then JB Weld.
PVC capped and PVC capped and interfaced with BNCs for interfaced with BNCs for wireswires
BNCPVC
JB WeldVacuum Epoxy
Scintillator
System Stabilization
The two PVC pipes bonded with ABS “glue”
Adds support for all system components
Tether passes through brass tube in center
Each PMT - Scintillator combination slides into frame.
Wood Frame
Brass Tube
The Exterior Box Materials
Reflective MylarReflective Mylar
InsulationInsulation
Foam CoreFoam Core
ThermoSheild PaintThermoSheild Paint
Aluminum tapeAluminum tape
EpoxyEpoxy
Coincidence Counting Circuit
Purpose:Purpose:
To supply each PMT with 5 VTo supply each PMT with 5 V
To time impulses from each PMT and To time impulses from each PMT and determine coincidencesdetermine coincidences
Send count impulses to data loggerSend count impulses to data logger
Coincidence Timing CircuitCoincidence Timing Circuit
Courtesy of Lawrence Berkeley National Laboratory
Circuit System SchematicCircuit System Schematic
Interfaces:Interfaces: Two PMT ModulesTwo PMT Modules
Two nine volt Two nine volt batteries in seriesbatteries in series
MadgeTech Data MadgeTech Data LoggerLogger
Circuit
Heater CircuitHeater Circuit
Six Resistors –Six Resistors – 3.9 3.9 ohm eachohm each 5 Watts each 5 Watts each
Three 9 Volt batteries Three 9 Volt batteries in parallelin parallel
Keep payload interior >Keep payload interior > 5 C5 C
Batteries in parallel
Resistors
Power BudgetPower Budget
18 Volts to the Coincidence Count Circuit 18 Volts to the Coincidence Count Circuit PMT modules High voltage source is housed within the PMT modules High voltage source is housed within the
PMT basePMT base
Power out – heater – 18 wattsPower out – heater – 18 watts 9 Volts to the heater circuit (three 9 V batteries in parallel)9 Volts to the heater circuit (three 9 V batteries in parallel)
Current requirments: Current requirments: 1934 mA1934 mA Heater - 1450 mAHeater - 1450 mA Circuit – 224 mACircuit – 224 mA PMT modules – 80 mA eachPMT modules – 80 mA each
Data CollectionData Collection
PurposePurpose::
Collect electronic Collect electronic pulses from the pulses from the circuitcircuit
Put a time stamp to Put a time stamp to each pulseeach pulse
Data Collection Data Collection SchematicSchematic
Computer Data Logger
Circuit
During FlightPost-Recovery
Mass Budget : 3000 gm Mass Budget : 3000 gm
2 Scintillator Panels 2 Scintillator Panels 415 grams415 gramsBrass rodBrass rod 34 grams 34 gramsBox Box 600 grams600 gramsFrameFrame 400 grams400 grams2 PMTs 2 PMTs 460 grams460 gramsPulse recorderPulse recorder 26 grams 26 gramsHobosHobos 61 grams 61 gramsBatteries Batteries 191 grams191 gramsHeaterHeater 37 grams 37 gramsCircuitCircuit 145 grams145 gramsCables, switchesCables, switches 100 grams100 grams
TotalTotal 2469 grams2469 grams
BudgetBudget
PMT ModulesPMT Modules ~ 2300.00~ 2300.00MadgeTech Data LoggerMadgeTech Data Logger ~ 195.00~ 195.00BatteriesBatteries ~ 100.00~ 100.00Box MaterialsBox Materials ~ 100.00~ 100.00LX 200LX 200 ~ 250.00~ 250.00Geiger tubeGeiger tube ~ 270.00~ 270.00CablesCables ~ 50.00~ 50.00Buffing CompoundBuffing Compound ~ 125.00~ 125.00Optical GreaseOptical Grease ~ 75.00~ 75.00Electronic componentsElectronic components ~ 50.00~ 50.00TotalTotal
____________________________________________________________________________________~3515.00~3515.00
Project OrganizationProject Organization Project Advisors:Project Advisors:
Dr. Robert WalchDr. Robert Walch Dr. Dick DietzDr. Dick Dietz Dr. Cynthia GalovichDr. Cynthia Galovich Dr. Kendall MalloryDr. Kendall Mallory
Project Manager:Project Manager: Pat MillsPat Mills
Electronics:Electronics: Julie SmithJulie Smith
Data Collection & Heater:Data Collection & Heater: Ryan MarshallRyan Marshall
PMT Module & PMT Module & Scintillator:Scintillator: Anna SamselAnna Samsel
System Housing & System Housing & Stabilization:Stabilization: Levi EllisLevi Ellis
ScheduleSchedule
April 5 – 10: Individual component testing Construct the housing and frame Construct the detector Construct the Geiger tube – Palmtop detector
April 11 – 16: Test the whole system Make any final adjustments
April 17 : Launch
AcknowledgementsAcknowledgementsDr. M. A. Duvernois University of MinnisotaDr. James Connell University of New HampshireDr. Howard Matis Lawrence Berkeley National
LaboratoryAndrew Loomis UNCKen Cochran UNCKodak PMTs purchased with
Electroptics Grant funds
Many Thanks to:
The Colorado Space Grant Consortium, NASA and JPL for giving us this wonderful opportunity
The UNC Dept. of Physics faculty; without whom, none of this would be possible