Cosmic Ray Flux Experiment

By GR² Team from LSU LaACESBy GR² Team from LSU LaACES

Science BackgroundScience Background

• Cosmic rays are high Cosmic rays are high energy particles energy particles hitting the Earth’s hitting the Earth’s atmosphereatmosphere

• The initial particle The initial particle breaks into a breaks into a multitude of different multitude of different particlesparticles

• We’re interested in the We’re interested in the gamma rays that gamma rays that result from this showerresult from this shower

Science Background, Science Background, continuedcontinued

• Lead-shielded GM Lead-shielded GM tube specialized for tube specialized for detecting gamma detecting gamma radiationradiation

• Gamma radiation Gamma radiation accounts for about accounts for about one-third of the one-third of the cosmic ray countcosmic ray count

Mission GoalsMission Goals

• To measure the flux of cosmic radiation To measure the flux of cosmic radiation (excluding gamma rays) as a function of (excluding gamma rays) as a function of altitudealtitude

• To measure the flux of overall radiation To measure the flux of overall radiation as a function of altitudeas a function of altitude

• To determine the flux of gamma To determine the flux of gamma radiation versus altituderadiation versus altitude

• To determine the ratio of gamma rays To determine the ratio of gamma rays to overall flux as a function of altitudeto overall flux as a function of altitude

Payload DesignPayload Design

• Flight control unit: BalloonSAT®Flight control unit: BalloonSAT®• Power source: three 3.6V AA lithium Power source: three 3.6V AA lithium

batteriesbatteries• Geiger Müller (GM) tube to measure cosmic Geiger Müller (GM) tube to measure cosmic

ray countray count• Lead-shielded GM tube to determine Lead-shielded GM tube to determine

gamma ray countgamma ray count• Insulation and padding for structureInsulation and padding for structure

System DesignSystem Design

• Balloon to payload Balloon to payload interface: straws interface: straws and stringsand strings

• Batteries power GM Batteries power GM tube boards & tube boards & BalloonSAT®BalloonSAT®

• GM tube boards GM tube boards connect to pins P2 connect to pins P2 (shielded) and P6 (shielded) and P6 (unshielded)(unshielded)

Electrical DesignElectrical Design

• Powered by three Powered by three 3.6V AA lithium 3.6V AA lithium batteriesbatteries

• BalloonSAT® is the BalloonSAT® is the flight control unitflight control unit

• Geiger-Müller tubes Geiger-Müller tubes connect to the FCU connect to the FCU via pads P2 and P6via pads P2 and P6

• Fuse rated to ensure Fuse rated to ensure safe operationsafe operation

Component Current Draw (mA) Voltage (V) Power (mAh)Gamma Ray Sensor 5 10.8 20Cosmic Ray Sensor 5 10.8 20BalloonSAT 50 10.8 200Total 60 10.8 240

Thermal DesignThermal Design

• Thermal tests were Thermal tests were conducted with various conducted with various Fom-Cor® set-ups and Fom-Cor® set-ups and polystyrenepolystyrene

• Polystyrene was Polystyrene was chosen since it is both chosen since it is both insulating and insulating and lightweightlightweight

• Recycled blown-in Recycled blown-in insulation is added insulation is added

• Reflective tape outsideReflective tape outside

Foam Tests

-80

-60

-40

-20

0

20

40

0 500 1000 1500 2000

Cell Number

Tem

per

atu

re (*

C)

Test 1: Black Foam w/o Inner Reflective Tape

Test 2: Black Foam Only

Test 3: Only White Foam

Test 4: Only Insulation

Test 5: White Foam and Insulation

Test 6: Yellow Foam

Test 7: Polystyrene Insulation

Mechanical DesignMechanical Design

• Lead thickness is Lead thickness is 0.6cm to detect 0.6cm to detect about 2/3 of the about 2/3 of the gamma raysgamma rays

• Sheets of lead form Sheets of lead form a partial cylinder a partial cylinder shield around the shield around the GM tubeGM tube

• Total weight: 615gTotal weight: 615g

Interaction Percentage vs. Mass

0

20

40

60

80

100

0 100 200 300 400 500

Mass (g)

Inte

racti

on

Perc

en

tag

e (

%)

Series1

Weight (in g) Component

64 Radiation sensor

64+Lead(163) Gamma Ray sensor

63 Balloon Sat

58 Power (Batteries)

69 Polystyrene InsulatingStructure

81 Wires and extras

53 Recycled Blown inInsulation

615 Total

Mechanical Design, cont.Mechanical Design, cont.

• Top view with vertical insertTop view with vertical insert• Recycled blown-in insulation added in Recycled blown-in insulation added in

open spaces (in plastic baggies)open spaces (in plastic baggies)

Mechanical Design, cont.Mechanical Design, cont.

• Top view, cont.Top view, cont.

• Side viewSide view

SoftwareSoftware

• Geiger modeGeiger mode• 256Kb memory chip 256Kb memory chip • Reset Basic Stamp programReset Basic Stamp program• Data acquisition program:Data acquisition program:

• time is set to standard time (Greenwich) to time is set to standard time (Greenwich) to synchronize with altitude datasynchronize with altitude data

• sampling intervals (each 18.1 seconds per sampling intervals (each 18.1 seconds per interval)interval)

• timestamp to correlate with altitudetimestamp to correlate with altitude

Software, cont.Software, cont.

• Data Retrieval:Data Retrieval:• certain steps need to be taken to get the raw certain steps need to be taken to get the raw

data into Exceldata into Excel• data for each tube is organized into four data for each tube is organized into four

columnscolumns

• Program to correlate counts with altitudeProgram to correlate counts with altitude• Filtering of data: Filtering of data:

• organization of Excel spreadsheetorganization of Excel spreadsheet• averaging three consecutive counts to yield an averaging three consecutive counts to yield an

average count per intervalaverage count per interval

Temperature TestTemperature Test

• Confirm the power source could last in upper Confirm the power source could last in upper atmosphere temperaturesatmosphere temperatures

• Confirm that there is no dependence of the Confirm that there is no dependence of the measurement on temperature measurement on temperature

• Payload passed the testPayload passed the test• was working when we took it out of the dry ice was working when we took it out of the dry ice

chamberchamber• data showed no dependency on the cold data showed no dependency on the cold

temperaturestemperatures

Pressure TestPressure Test

• Because our vacuum source was not Because our vacuum source was not operational, a pressure test was impossibleoperational, a pressure test was impossible

• We verified that each material would not We verified that each material would not “blow up” in the low pressure environment“blow up” in the low pressure environment

• We determined from past flights using the We determined from past flights using the same materials that we would not encounter same materials that we would not encounter any issuesany issues

Shock TestShock Test

• The payload was dropped from a height of The payload was dropped from a height of 10 feet to simulate the force felt upon 10 feet to simulate the force felt upon landing because the nominal descent rate is landing because the nominal descent rate is approx. 20 feet/sec.approx. 20 feet/sec.

• The drop moved the switches on the GM The drop moved the switches on the GM tubes, so we put electrical tape on the tubes, so we put electrical tape on the switches to hold them in place.switches to hold them in place.

• Nothing was damagedNothing was damaged

AcknowledgementsAcknowledgements

• CSBFCSBF• Dr. GuzikDr. Guzik• Dr. WefelDr. Wefel• Mr. GiammancoMr. Giammanco• Mr. EllisonMr. Ellison• Dr. CherryDr. Cherry• Mr. GrangerMr. Granger• And their loving families!!!And their loving families!!!• NASANASA