By GR² Team from LSU LaACES

Science Background Cosmic rays are high energy particles constantly hitting the Earth’s atmosphere Cosmic rays are high energy particles constantly hitting the Earth’s atmosphere An initial particle may break into a multitude of different particles (shower) An initial particle may break into a multitude of different particles (shower) We are interested in the gamma rays that result from this shower We are interested in the gamma rays that result from this shower

Science Background, continued Gamma radiation accounts for about one-third of the cosmic ray count Gamma radiation accounts for about one-third of the cosmic ray count Specialized lead- encased GM tube for detecting gamma rays Specialized lead- encased GM tube for detecting gamma rays

Mission Goals To measure the flux of cosmic radiation (excluding gamma rays) as a function of altitude To measure the flux of cosmic radiation (excluding gamma rays) as a function of altitude To measure the flux of overall radiation as a function of altitude To measure the flux of overall radiation as a function of altitude To determine the flux of gamma radiation versus altitude To determine the flux of gamma radiation versus altitude To determine the ratio of gamma rays to overall flux as a function of altitude To determine the ratio of gamma rays to overall flux as a function of altitude

Payload Design Flight control unit: BalloonSAT® Flight control unit: BalloonSAT® Power source: three 3.6V AA lithium batteries Power source: three 3.6V AA lithium batteries Geiger Müller (GM) tube to measure cosmic ray count (connected to P0 on the BalloonSAT®) Geiger Müller (GM) tube to measure cosmic ray count (connected to P0 on the BalloonSAT®) Lead-shielded GM tube to determine gamma ray count (connected to P1 on the BalloonSAT®) Lead-shielded GM tube to determine gamma ray count (connected to P1 on the BalloonSAT®) Polystyrene insulation for structure Polystyrene insulation for structure Recycled blow-in insulation for extra thermal control Recycled blow-in insulation for extra thermal control After FRR, it was determined we would need to add a heat pack to ensure the BalloonSAT® would stay warm enough to function throughout the tropopause After FRR, it was determined we would need to add a heat pack to ensure the BalloonSAT® would stay warm enough to function throughout the tropopause After first flight, a desiccant pack was added to absorb moisture After first flight, a desiccant pack was added to absorb moisture

Payload Design, cont.

Calibrations Need to calibrate the different components of flux Need to calibrate the different components of flux We will only be measuring a count We will only be measuring a count Need to convert to flux Need to convert to flux Time Time Need uncertainty in time interval before calculating the error in counts per second Need uncertainty in time interval before calculating the error in counts per second Pulser test Pulser test Known amount of “counts,” able to determine time interval error Known amount of “counts,” able to determine time interval error Both pins: 18.1 ± 0.4 seconds Both pins: 18.1 ± 0.4 seconds Area Area Tool: caliper Tool: caliper 6.17 ± 0.02 cm ± 0.02 cm 2

Calibrations, cont. Counts/second Counts/second First, normalization: First, normalization: Example raw data: 512 intervals and 1,831 counts (shielded), 1,914 counts (unshielded) Example raw data: 512 intervals and 1,831 counts (shielded), 1,914 counts (unshielded) Shielded tube: ± counts/sec Shielded tube: ± counts/sec Unshielded tube: ± counts/sec Unshielded tube: ± counts/sec Second, energy cutoff test: Second, energy cutoff test: Shielded tube: 0.36 ± 0.01 Shielded tube: 0.36 ± 0.01 Unshielded tube 0.36 ± 0.01 Unshielded tube 0.36 ± 0.01 Solid Angle – calculations Solid Angle – calculations Set muon flux at sea level is counts/(cm 2 *sec*str) Set muon flux at sea level is counts/(cm 2 *sec*str) Plug in above numbers; Ω = 4.79 ± 0.03 str Plug in above numbers; Ω = 4.79 ± 0.03 str

Discrepancies in Data The average count per interval for normalization (muons at sea level) was about 3.7 counts/int The average count per interval for normalization (muons at sea level) was about 3.7 counts/int For system testing: 6.5 counts/int For system testing: 6.5 counts/int BalloonSAT ® was rewired after the normalization run BalloonSAT ® was rewired after the normalization run A wire was mistakenly left connecting the P2 and P6 slots on the back of the board A wire was mistakenly left connecting the P2 and P6 slots on the back of the board This almost doubled the expected number of counts because of the connection This almost doubled the expected number of counts because of the connection This was found after the first flight and fixed for the second flight This was found after the first flight and fixed for the second flight

Summary of Flight 1 Flight Launch and Recovery very successful Flight Launch and Recovery very successful Payload survived shock of landing Payload survived shock of landing BalloonSAT ® reset shortly after landing BalloonSAT ® reset shortly after landing Seemed to survive thermally (except for the issue of condensation) Seemed to survive thermally (except for the issue of condensation) When opening box after retrieval, the positive battery lead was disconnected from the BalloonSAT ® When opening box after retrieval, the positive battery lead was disconnected from the BalloonSAT ® Determined to have happened when opening the box Determined to have happened when opening the box Data had three full sets of zeroes Data had three full sets of zeroes Two sets corresponded to payload laying horizontally (implies faulty power connections) Two sets corresponded to payload laying horizontally (implies faulty power connections) One set corresponds to expected peak of data (software issue) One set corresponds to expected peak of data (software issue)

Issues from Flight 1 Condensation Condensation Shaky solder joints Shaky solder joints Software error Software error Zeroes within data (consequence of above) Zeroes within data (consequence of above) So in combination with other errors by other teams, we decided to fly again So in combination with other errors by other teams, we decided to fly again

Flight 2 Preparations Condensation Condensation Added Tidy Cats® as a desiccant Added Tidy Cats® as a desiccant Mass of packet increased by 6 grams Mass of packet increased by 6 grams Electronics Electronics Inspected and fixed solder joints and wires Inspected and fixed solder joints and wires Replaced BalloonSAT ® board Replaced BalloonSAT ® board Software error Software error Switched count variables from Bytes to Word to save larger values Switched count variables from Bytes to Word to save larger values

Summary of Flight 2

Summary of Flight 2, cont. Flight was successful, but retrieval was a bit tricky Flight was successful, but retrieval was a bit tricky Payload survived the shock (did not land as hard because of the tree) Payload survived the shock (did not land as hard because of the tree) Payload survived thermal conditions Payload survived thermal conditions Received accurate data from the unshielded tube Received accurate data from the unshielded tube Leaded tube responded on the ground and up to 30,000 feet Leaded tube responded on the ground and up to 30,000 feet

Issues from Flight 2 Data for leaded tube is presumed to be inaccurate Data for leaded tube is presumed to be inaccurate Deduced to be connections failing in the cold temperatures (early on in flight) Deduced to be connections failing in the cold temperatures (early on in flight)

Counts vs. Altitude

Flux & Geometry Factor Flux (φ)= counts / (area*time*steridian) Flux (φ)= counts / (area*time*steridian) Geometry factor (AΩ)= area*steridian Geometry factor (AΩ)= area*steridian Using calibrations of ground data: Using calibrations of ground data: counts/sec =.207 counts/sec =.207 area = 6.17 cm 2 area = 6.17 cm 2 flux at ground level = counts/(cm 2 *s*sr) flux at ground level = counts/(cm 2 *s*sr) AΩ = 29.6 cm 2 *sr throughout flight AΩ = 29.6 cm 2 *sr throughout flight

Cosmic Ray Flux vs. Altitude

Error Propagation: Altitude dh = sqrt[ (1/3)*(dh1)² + (1/3)*(dh2)² + (1/3)*(dh3)²] GPS altitude error=dh1=dh2=dh3=100 ft dh= 100 / (sqrt(3)) ft Due to systematic error in the GPS tracking system

Error Propagation: Gamma Rays and Ratios Consistent data from the lead-shielded GM tube is necessary for accurate graphs and error determinations (in line with our mission goals) Consistent data from the lead-shielded GM tube is necessary for accurate graphs and error determinations (in line with our mission goals) Gamma ray flux = overall flux - non-γ flux Gamma ray flux = overall flux - non-γ flux σ γ = sqrt[σ o 2 + σ non-γ 2 ] σ γ = sqrt[σ o 2 + σ non-γ 2 ] Ratio = gamma ray flux/overall flux Ratio = gamma ray flux/overall flux σ r = sqrt[(1/ φ o ) 2 σ γ 2 + (φ γ /(φ o ) 2 ) 2 σ o 2 ] σ r = sqrt[(1/ φ o ) 2 σ γ 2 + (φ γ /(φ o ) 2 ) 2 σ o 2 ]

Flux with Error

Analyzing the Gamma Count The leaded GM tube began to fail at about 30,000 feet at -14°C The leaded GM tube began to fail at about 30,000 feet at -14°C This seemed too warm of an ambient temperature for a sensor to fail, as compared to previous flights and thermal tests This seemed too warm of an ambient temperature for a sensor to fail, as compared to previous flights and thermal tests Obtaining a gamma count became impossible because the payload did not rise to an altitude suitable for “measuring” gamma rays before the sensor began to fail Obtaining a gamma count became impossible because the payload did not rise to an altitude suitable for “measuring” gamma rays before the sensor began to fail

Acknowledgements Tidy Cats Kitty Litter Tidy Cats Kitty Litter CSBF CSBF Dr. Guzik Dr. Guzik Dr. Wefel Dr. Wefel Mr. Giammanco Mr. Giammanco Mr. Ellison Mr. Ellison Dr. Cherry Dr. Cherry Mr. Granger Mr. Granger And their loving families!!! And their loving families!!! NASA NASA