LA ACES Neutron Detector (NeD) Team Members: Ravi Chimmalgi Robert Giglio Shiloh Meyers Bradley Wood Louisiana State University LaAces Amateur Balloon

LA ACESLA ACESNeutron Detector (NeD)Neutron Detector (NeD)

Team Members: Ravi Chimmalgi

Robert Giglio

Shiloh Meyers

Bradley Wood

Louisiana State University LaAces Amateur Balloon Flight Program

Cosmic Rays: Supernova DebrisCosmic Rays: Supernova Debris

http://upload.wikimedia.org/wikipedia/commons/thumb/4/43/Supernova-1987a.jpg/660px-Supernova-1987a.jpg


http://auger.cnrs.fr/presse/0197swordy2a.gif

Cosmic Rays: Supernova Debris ContCosmic Rays: Supernova Debris Cont


Cosmic Rays: Coming to EarthCosmic Rays: Coming to Earth

http://www.astroparticlephysics.nl/cosmic_rays.jpg


Cosmic Rays: Cosmic Shower and Cosmic Rays: Cosmic Shower and Neutron ProductionNeutron Production

http://neutronm.bartol.udel.edu/catch/cr2b.gifLouisiana State University LaAces Amateur Balloon Flight Program

Neutron Flux as Measured Aboard High Neutron Flux as Measured Aboard High Altitude PlaneAltitude Plane


Measuring Neutron Flux in Atmosphere: Measuring Neutron Flux in Atmosphere: Science GoalsScience Goals

• Measure neutron flux as a function of altitude.

• Differentiate neutrons from other interacting particles.

• Create a graphical representation to present neutron flux versus altitude.

• Give a definite statement on the safety issues present for airline passengers from the data found


Measuring Neutron Flux in Atmosphere: Measuring Neutron Flux in Atmosphere: Scientific RequirementsScientific Requirements

• Need to record at least one data point every 10 minutes, or an average of every 10000 ft (3.048 km) in order to reproduce the accuracy of previously observed data plots

• Payload instrumentation must function for at least 4 hrs

• Payload instrumentation must function at pressures as low as 10 mBars

• Payload instrumentation must function at atmospheric temperatures as low as -60 degrees Celsius

• Need to make measurements in altitude range of airline traffic (30000ft-40000ft).


Measuring Neutrons at High Altitudes: Measuring Neutrons at High Altitudes: ConditionsConditions

http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.gif


Altitude vs TemperatureAltitude vs Temperature

http://www.seungjoo.net/projects/may2006/image2/clip_image039.jpgLouisiana State University LaAces Amateur Balloon Flight Program

Measuring Neutrons at High Altitudes: Measuring Neutrons at High Altitudes: DetectorDetector

http://www.sphere.bc.ca/test/tubes/252-rca-6655a.jpghttp://www.apace-science.com/eljen/images/plastic.jpg

PMT Scintillation Plastic


Detector Continued: Neutron ScatterDetector Continued: Neutron Scatter

http://knowledgepublications.com/doe/images/DOE_Nuclear_Elastic_Scattering.gif

~500 keV to photons

1 MeV


Detector Continued: Neutron Absorption Detector Continued: Neutron Absorption

Alpha Deposition ~2.8 MeV


Previous Data At Palestine, TexasPrevious Data At Palestine, Texas

Ground = .002 neutrons cm^-2/s (10keV – 10 MeV)

Max Balloon Altitude = .04 neutrons cm^-2/s (20-120 MeV)

Based on D. J. Forest and E. L. Chupp (1968). Upper

Limit for the Solar Neutron Flux in the Energy Interval 20-120 MeV. Kluwer Academic Publishers.


Overview of electronicsOverview of electronics

Photomultiplier & boron-doped scintillator used

Produced By LA ACES Team F. N. H. S.


How the PMT worksHow the PMT works

Light emitted by scintillatorPMT detects light & sends pulse

to circuit



Timing the WindowsTiming the Windows

Pulses specific times apartCircuit detects first pulse, closes window for

150nsWindow opened

for 20us



Louisiana State University Physics and Astronomy

Electronics block diagramElectronics block diagram


Payload OverviewPayload OverviewSolidWorks® Model of Mechanical Payload

Sensor System

Sensor System

ControlControl CircuitryCircuitry

ControlControl CircuitryCircuitry

Batteries & HolderBatteries & Holder


Insert (Front-side)Insert (Front-side)

Photo of Insert


Insert (Back-side)Insert (Back-side)


• PMT/ Scintillator sensor neutron detectors >2kg (2000g)

• Our Total Weight: ~1100g

WeightWeight

Box 230 g

Circuits 190 g

Insert 90 g

Power & Cables 210 g

PMT 280 g

Misc. 100g


SoftwareSoftware

Three different programs: pre-flight, on-flight and post-flight.

Fail-Safe mechanismSample rate = 10 secEach data point = 13 bytes


Pre-flight ProgramPre-flight Program

START ENDFOR ADDR =

0 to $7FFFof EEPROM

STORE$FF

INITIALIZE realtime clock by

writing thetime to the

correspondingaddresses in

the clockregister.


On-flight ProgramOn-flight ProgramSTART

END

Set countersto event

counter mode

ADDR = ADDR + 13

Enoughmemory?

NO

YES

ADDR = 0

READEEPROM

IS EEPROM= $FF ?

ADDR = ADDR + 1

START counters

WAIT 10 sec

STOP counters

READcounters,time andtemperat

ure

STORE thedata

NO

YES


Post-flight ProgramPost-flight Program

START ENDFOR Addr = 0to $7fff

READ & PRINTAddr.

New line

ISADDR>=$7fff

?

YES

NO

Addr = Addr +13

FOR x=1 to 13



Flight Data HandlingFlight Data Handling

Used Term232 and Excel.Altitude readings from the GPS. Data analysis.

- Neutron Count vs Altitude - Particle Count vs Altitude - Temperature vs Time


Took ground level counts in Palestine

Integrate data in 10 second intervals versus altitude

Integrate data in 5 minute intervals

Apply error deviation using following Poisson equations

Procedure of Data AnalysisProcedure of Data Analysis

Ground Count ComparisonsGround Count Comparisons


Measured Neutron Flux vs Altitude (10 Measured Neutron Flux vs Altitude (10 Sec)Sec)


Measured Neutron Flux vs Altitude (5 Measured Neutron Flux vs Altitude (5 min)min)



Compare data to previously recorded data

Compare data to neutron radiation levels for biological organisms

Procedure of Data Analysis ContProcedure of Data Analysis Cont

Predicted Neutron Flux vs AltitudePredicted Neutron Flux vs Altitude

Predicted neutron flux as a function

of altitude F. N. H. S.Louisiana State University LaAces Amateur Balloon Flight Program

Measured Neutron Counts vs Altitude (5 Measured Neutron Counts vs Altitude (5 min)min)


We Detected a Neutron Calibration Source



Californium Source

0

10

20

30

40

50

60

0:20:10 0:21:36 0:23:02 0:24:29 0:25:55 0:27:22 0:28:48 0:30:14 0:31:41 0:33:07

Time (s)

Co

un

ts

Predicted Charged Particle FluxPredicted Charged Particle Flux

Predicted measurements of cosmic ray flux given by LA ACE’s experiment FRED.


Measured Charged Particle FluxMeasured Charged Particle Flux


Atmospheric TemperatureAtmospheric Temperature


Predicted measurements of temperature given by LA ACE’s experiment TIC.

Measured Internal Temperature vs TimeMeasured Internal Temperature vs Time


Biological Radiation in Equivalent Biological Radiation in Equivalent DosagesDosages

Equivalent dose measured in Sieverts

1 Sievert causes nauseation 2 Sieverts causes hair loss6 Sieverts kills

Conversion equation: DE = R(E) φ


Neutron Dose vs AltitudeNeutron Dose vs Altitude


Charged Particle Counts Over Total FlightCharged Particle Counts Over Total Flight


Charged Particle Counts At LaunchCharged Particle Counts At Launch


Launch Particle Counts

0

10

20

30

40

50

60

70

300 600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 3900 4200 4500

Altitude (feet)

Pa

rtic

le C

ou

nts

High Threshold

Low Threshold

Thank you

Jim Adams and Mark Christl at Marshal Space Center

Dr. Erno SajoDr. Jeff BlackmonColumbia Scientific Ballooning Facility

Documents

LA ACES Neutron Detector (NeD) Team Members: Ravi Chimmalgi Robert Giglio Shiloh Meyers Bradley Wood Louisiana State University LaAces Amateur Balloon