CosmicSatCosmicSat University of Northern Colorado April 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 PMT Scintillator Coincidence Circuit Data Logger Batteries Heater Circuit 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 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 scintillator The PMTs bonded to scintillator Organic Scintillator wrapped in Mylar foil and electrical tape Organic Scintillator wrapped in Mylar foil and electrical tape PMTs wired to coincidence circuit via BNCs PMTs wired to coincidence circuit via BNCs Scintillator PMT Scintillator Charged Particles Optical Grease Vacuum Epoxy

PMTs and Scintillator Housing: Housing: PMTs encased in PVC pipe – maintain atmospheric pressure PMTs encased in PVC pipe – maintain atmospheric pressure PMT – scintillator joined with vacuum epoxy and then JB Weld. PMT – scintillator joined with vacuum epoxy and then JB Weld. PVC capped and interfaced with BNCs for wires PVC capped and interfaced with BNCs for wires BNCPVC JB Weld Vacuum 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 Mylar Reflective Mylar Insulation Insulation Foam Core Foam Core ThermoSheild Paint ThermoSheild Paint Aluminum tape Aluminum tape Epoxy Epoxy

Coincidence Counting Circuit Purpose: Purpose: To supply each PMT with 5 V To supply each PMT with 5 V To time impulses from each PMT and determine coincidences To time impulses from each PMT and determine coincidences Send count impulses to data logger Send count impulses to data logger

Coincidence Timing Circuit Courtesy of Lawrence Berkeley National Laboratory

Circuit System Schematic Interfaces: Interfaces: Two PMT Modules Two PMT Modules Two nine volt batteries in series Two nine volt batteries in series MadgeTech Data Logger MadgeTech Data Logger Circuit

Circuit: Start to Finish Courtesy of Lawrence Berkeley National Laboratory

Heater Circuit Six Resistors – Six Resistors – 3.9 ohm each 3.9 ohm each 5 Watts each 5 Watts each Three 9 Volt batteries in parallel Three 9 Volt batteries in parallel Keep payload interior > Keep payload interior > 5 C 5 C Batteries in parallel Resistors

Power 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 base PMT modules High voltage source is housed within the PMT base Power out – heater – 18 watts Power 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: 1934 mA Current requirments: 1934 mA Heater mA Heater mA Circuit – 224 mA Circuit – 224 mA PMT modules – 80 mA each PMT modules – 80 mA each

Data Collection  Purpose :  Collect electronic pulses from the circuit  Put a time stamp to each pulse

Data Collection Schematic Computer Data Logger Circuit During FlightPost-Recovery

Mass Budget : 3000 gm 2 Scintillator Panels 415 grams Brass rod 34 grams Box 600 grams Frame400 grams 2 PMTs 460 grams Pulse recorder 26 grams Hobos 61 grams Batteries 191 grams Heater 37 grams Circuit145 grams Cables, switches100 grams Total2469 grams

Budget PMT Modules~ MadgeTech Data Logger~ Batteries~ Box Materials~ LX 200~ Geiger tube~ Cables~ Buffing Compound~ Optical Grease~ Electronic components~ Total __________________________________________ ~

Project Organization Project Advisors: Project Advisors: Dr. Robert Walch Dr. Robert Walch Dr. Dick Dietz Dr. Dick Dietz Dr. Cynthia Galovich Dr. Cynthia Galovich Dr. Kendall Mallory Dr. Kendall Mallory Project Manager: Project Manager: Pat Mills Pat Mills Electronics: Julie Smith Data Collection & Heater: Ryan Marshall PMT Module & Scintillator: Anna Samsel System Housing & Stabilization: Levi Ellis

Schedule 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 Payload Geiger Tube – Palmtop Computer

Acknowledgements Dr. M. A. Duvernois University of Minnisota Dr. James Connell University of New Hampshire Dr. Howard Matis Lawrence Berkeley National Laboratory Andrew Loomis UNC Ken Cochran UNC Kodak 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