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

Housing Prototype

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

Circuit: Start to FinishCircuit: Start to Finish

Courtesy of Lawrence Berkeley National Laboratory

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

Alternate PayloadAlternate PayloadGeiger Tube – Palmtop Geiger Tube – Palmtop

ComputerComputer

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