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LaACES Program
Pre-Preliminary Design Review Document
for the
Cosmic Ray
Experiment
by
Team
Cosmic
Prepared by:
Jace Boudreaux
Date
Allen Bordelon
Date
Institution Signoff (replace with name)
Date
Institution Signoff (replace with name)
Date
LAACES Signoff
Date
Submitted:
Reviewed:
Revised:
Approved:
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TABLE OF CONTENTS
Cover............................................................................................................................................. i
Table of Contents......................................................................................................................... ii
List of Figures ............................................................................................................................. iii
List of Tables .............................................................................................................................. iii
1.0 Document Purpose ..................................................................................................................1
1.1 Document Scope ...............................................................................................................1
1.2 Change Control and Update Procedures ...........................................................................1
2.0 Reference Documents .............................................................................................................1
3.0 Goals, Objectives, Requirements............................................................................................3
3.1 Mission Goal.....................................................................................................................3
3.2 Objectives .........................................................................................................................3
3.3 Science Background and Requirements ...........................................................................4
3.4 Technical Background and Requirements ........................................................................6
9.0 Master Schedule......................................................................................................................8
9.1 Work Breakdown Structure (WBS) ..................................................................................8
9.2 Staffing Plan......................................................................................................................8
9.3 Timeline and Milestones...................................................................................................8
12.0 Glossary ...............................................................................................................................9
Pre-PDR Note: Sections 4 through 8 as well as sections 10 through 11 will be provided in a
later document. In addition, for the Pre-PDR only a portion of 9.2 and 9.3 needs to be
complete (see details in section 9).
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LIST OF FIGURES
Figure 1 – Primary Cosmic Ray Cascading into Secondary Cosmic Rays……………..………. 4
Figure 2 – Graph of Cosmic Radiation with Increasing Altitude ……………………………… 5
Figure 3 – Gantt Chart Schedule of Major Project Tasks ……………………………………… 8
LIST OF TABLES
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1.0 Document Purpose
This document describes the preliminary design for the Cosmic Ray experiment by Team
Cosmic for the LAACES Program. It fulfills part of the LAACES Project requirements for the
Preliminary Design Review (PDR) to be held December 1, 2009.
1.1 Document Scope
This PDR document specifies the scientific purpose and requirements for the Cosmic Ray
experiment and provides a guideline for the development, operation and cost of this payload
under the LAACES Project. The document includes details of the payload design, fabrication,
integration, testing, flight operation, and data analysis. In addition, project management,
timelines, work breakdown, expenditures and risk management is discussed. Finally, the designs
and plans presented here are preliminary and will be finalized at the time of the Critical Design
Review (CDR).
1.2 Change Control and Update Procedures
Changes to this PDR document shall only be made after approval by designated representatives
from Team Cosmic and the LAACES Institution Representative. Document change requests
should be sent to Team members and the LAACES Institution Representative and the LAACES
Project.
2.0 Reference Documents
1
Dacey, James. “Thunderclouds accelerate cosmic electrons.” Physics World. 2009. 25 Nov.
2009 <http://physicsworld.com/cws/article/news/39784>.
2
Dwyer, Joseph. “Do cosmic rays cause lightning?” Scientific America. 2008. 25 Nov. 2009
<http://www.scientificamerican.com/article.cfm?id=experts-do-cosmic-rays-cause-lightning>.
3
Nave, R. “Cosmic Rays.” Hyper Physics. 25 Nov. 2009 <http://hyperphysics.phyastr.gsu.edu/HBASE/Astro/cosmic.html>.
4
“How Do Thunderstorms Create Lightning? High-Energy Particles From Space Used To Probe
Thunderstorms.” Science Daily. 2009. 25 Nov. 2009
<http://www.sciencedaily.com/releases/2009/06/090601140934.htm>.
5
“The FRED Experiment.” LSU Space Sciences Group. 25 Nov. 2009
<http://laspace.lsu.edu/aces/teams/2002-2003/FLUX/FLUX.php>.
6
“Scintillation Counter.” Nuclear Power Fundamentals. 25 Nov. 2009
<http://www.tpub.com/content/doe/h1013v2/css/h1013v2_70.htm>.
7
“The Geiger-Mueller Counter.” Uranium Minerals. 25 Nov. 2009
<http://www.uraniumminerals.com/Tutorials/G-M_Counter/G-M_Counter.htm>.
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8
“Solid-State Detector.” Encyclopedia Britannica. 25 Nov. 2009
<http://www.britannica.com/EBchecked/topic/553347/solid-state-detector>.
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3.0 Goals, Objectives, Requirements
3.1 Mission Goal
To build a balloon payload that will measure radiation intensity as a function of altitude up to
100,000 feet and to compare this with electrical conductivity results from team Jupiter. This
may have a relationship to electrical conductivity of the atmosphere which could be related to the
cause of lightning.
3.2 Objectives
3.2.1 Science Objectives
-
Measure amount of ionizing radiation in the atmosphere as a function of altitude.
Distinguish between high and low energy radiation particles as a function of altitude.
Coordinate results with team Jupiter.
Analyze measured data.
3.2.2 Technical Objectives
-
Design and build an electrical system that can:
o Withstand atmosphere conditions up to 100,000 feet
o Count the number of radiation hits as a function of time
o Measure the energy of a radiation particle as a function of time
o Monitor temperature and pressure to make sure it is in range of sensors
o Record collected data and retrieve using a program
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3.3 Science Background and Requirements
3.3.1 Science Background
Cosmic rays are classified as primary and secondary. Primary cosmic rays are subatomic
particles, typically having energy levels in the billions of electron volts, which originate in outer
space. The breakdown of primary cosmic rays is approximately 90% hydrogen protons, 9%
alpha particles, 1% electrons, and a small portion light elements such as lithium and beryllium3.
When a primary cosmic ray hits the earth’s atmosphere, a nuclear reaction occurs between the
cosmic particle and an air particle (Figure 1). The primary cosmic ray breaks down into pions
and kaons. A neutral pion can decay into a positron, electron, and gamma ray. Charged pions
can decay to muons and muon antineutrinos. A positive pion can decay to a muon and a muon
antineutrino. Kaons can decay to muons. Gamma rays and muons can decay into electrons and
positrons. All particles created as a result of the primary cosmic ray and air molecule interaction
are secondary cosmic rays. The amount of particle transformations that will occur is determined
by the initial energy of the cosmic ray and the molecules that the particle is colliding with.
Figure 1 – Primary Cosmic Ray Cascading into Secondary Cosmic Rays3
Cosmic rays may be linked to lightning. Lightning is an electrical discharge in the air from a
cloud to the ground, which requires a strong electric field2. The cause of the high strength
electric field is unknown and is possibly caused by cosmic rays4. Cosmic rays produce ions in
the atmosphere, which will have an effect on electrical conductivity. Electrical conductivity is a
function of the electrical field. Lightning also produces gamma rays1, which can be produced in
the cosmic particle cascade. Researchers at the Cosmic Ray Laboratory of Japan’s RIKEN
research institute were able to detect electrons and gamma rays coming from a cloud at the same
time1.
Beginning at the initial primary cosmic ray and air interaction, cosmic radiation is expected to
increase as altitude decreases. Cosmic radiation will then reach a peak and decrease as it loses
its energy from cascading and interacting with air molecules. Low levels of cosmic radiation at
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ground level is expected. Previous LAACES Team FLUX flew a payload in 2003 measuring
cosmic radiation5. Figure 2 shows their graph of radiation counts versus altitude. Team FLUX’s
results are the expected results for a flight of this project’s end payload. In their experiment, the
cosmic radiation peaked at around 65,000 feet. It is expected that there will be more high energy
particles present at higher altitudes.
Figure 2 – Graph of Cosmic Radiation with Increasing Altitude5
3.3.2 Science Requirements
-
To measure rate of ionizing radiation in counts/minute as a function of altitude
To measure the energy of radiation particles as a function of altitude.
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3.4 Technical Background and Requirements
3.4.1 Technical Background
The payload will be attached to a balloon that will be rising at around 1000 feet/minute. It will
then be released and parachute back to the ground. A separate payload, flying on the same
balloon will measure altitude as a function of time. The payload is going to measure number of
cosmic ray particles and intensities of those particles at a specific time. This count can be related
to altitude through the time the sample was taken. There are several sensors that may be used to
achieve this, but their general principles of operation are similar. When a radiation particle
reacts with the sensor, a current pulse is produced. To measure counts per unit time, these pulses
will be conditioned to a voltage spike and counted by the BalloonSat. To measure the intensity
of the radiation particles, a radiation sensor with a pulse proportional to the intensity of the
particle must be used. This current pulse can then be converted into a voltage spike that varies
with intensity and measured by the BalloonSat.
Below is a list of radiation detectors available and their basic principles of operation.
Geiger Muller Counter – Small Glass or Mica tube filled with low pressure inert gas such as
helium, neon, or argon. There is a wire passing through the center, the anode, and the tube’s
walls are either metal or coated in metal to form the cathode. There is a voltage of several
hundred volts between the two but no current passing from the anode to the cathode.
When ionizing radiation hits the tube, it produces positive ions and electrons. The ions then gain
sufficient energy to ionize other gas molecules creating an avalanche affect7. These ions then
collide with the anode and produce a short current pulse that can be measured. The pulse is not
proportional to the initial radiation energy due to acceleration on the electrons by the field.
Semi-conductor radiation detector – Ionizing radiation produces free electrons and holes
between two electrodes8. The number of electron hole pairs is proportional to the energy of the
radiation transmitted to the semiconductor. Under an electric field these electrons and holes
travel to the electrodes, producing a current pulse. The current pulses produced are proportional
to the number of electron-hole pairs that collide with the electrodes. This pulse can then be
measured by another circuit and the energy of the radiation particle can be determined.
Scintillation counter – The sensor of a scintillator is a transparent crystal or plastic that emits
light when struck by ionizing radiation6. A photo multiplier tube measures the light intensity
being produced and transforms in into a proportional current pulse. The radiation can then be
counted and measured by the output of the photo multiplier tube. Since the current pulse is
proportional, the energy of the initial particle can be measured.
3.4.2 Technical Requirements
- Take sample rate in counts/minute every 1000 feet.
- Convert a current pulse into a voltage pulse.
- Store a time stamp for each count. It will use 3 bytes per measurement.
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- Condition a voltage value to the range of the ADC (0 to 3 volts) of the BalloonSat for each
energy proportional voltage pulse.
- Store a voltage value and a time stamp on the BalloonSat for each energy proportional voltage
pulse. It will use 4 bytes per measurement.
- Temperature and pressure need to be recorded to ensure sensors are in a workable range. This
will take an additional 2 bytes per measurement.
- Balloon payload should be less than 500 grams.
- Payload needs to withstand temperatures between -70 °C and 50°C
- Payload cannot exceed 3 oz / inch2 on any side
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9.0 Master Schedule
9.1 Work Breakdown Structure (WBS)
9.2 Staffing Plan
Project Management: Jace Boudreaux
Science Requirements: Allen Bordelon
Electronics: Allen Bordelon
Flight Software: Allen Bordelon
Mechanical: Jace Boudreaux
Integration: Jace Boudreaux
System Testing: Allen Bordelon
Calibrations: Jace Boudreaux
Data Processing and Analysis: Allen Bordelon
Documentation: Jace Boudreaux
9.3 Timeline and Milestones
Figure 3 – Gantt Chart Schedule of Major Project Tasks
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12.0 Glossary
[Define any terms that are used in your document. See below for examples.]
LAACES
CDR
FRR
PDR
TBD
TBS
WBS
ADC
Physics & Aerospace Catalyst Experiences in Research
Critical Design Review
Flight Readiness Review
Preliminary Design Review
To be determined
To be supplied
Work breakdown structure
Analog to digital converter
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