U N I V E R S I T Y L a f a y e t t e OF LOUISIANA RockSat 2010 Team CajunSat Mark Roberts Dr. Andy Hollerman Department of Physics University of Louisiana at Lafayette Lafayette, Louisiana June 23, 2010

Graduate student Mark Roberts decided to design and build an improved Geiger counter from the component that could detect cosmic rays from high altitude or near Earth space. We decided to participate in both the LASPACE HASP 2009 and RockSat programs for this payload. Mark will use his work on these projects for his Master’s degree research. RockSat Objectives

Functional Block Diagram

Systems Layout: Electronics Plate

Subsystems Layout

Micro Controller Board

Geiger-Mueller Tubes LND 7134 LND 72118

8 What is Dead Time? Dead Time : The minimum time between detectable pulses will be less than the recovery time. This is the pulse resolving time. Non-paralyzable dead-time: is defined as an event that occurs during this period is not counted nor does it influence the ability of the tube to respond to later events. Paralyzable dead time (resolve time): is the time duration between the end of the non- paralyzable dead time and a resolving point at which a pulse larger than the discriminator level can be developed.

Split Source Method to determine Dead Time A split radiation source is nothing more than a radioactive source that is split into two pieces. The source as a hole is considered to be the combined sources of N 1 and N 2 therefore I will call it N C. N 1 is the left side of the split source for me; making N 2 the right side of N C. Counts are taken from N 1, N 2, and N C sources with the same time duration. Then the dead time of the system can be calculated by [seconds] I made my own split source with some Uranyl Acetate that was laying around which happens to contain Uranium 238! =o)

10 Geiger Plateaus

11 Geiger Counter

Structure Subsystem We have already milled the platforms. Also all structure hardware (standoffs, bolts/nuts) has been received. Air tight chamber for static port Also have Polyethylene tubing (1/4’’ x.170’’ x 25 ft) fitted with a ¼’’ OD x ¼” NPT connector.

The Stay Puft Test The average off the shelf Marshmallow is a foam object with closed wall air cells within the foam. By placing a Marshmallow in a Vacuum the walls will expand with reduction of pressure; when air is allowed back into the chamber the walls collapse hence the marshmallow rapidly deflates to a shriveled state from it’s original form. By placing a Marshmallow in a Vacuum the walls will expand with reduction of pressure; when air is allowed back into the chamber the walls collapse hence the marshmallow rapidly deflates to a shriveled state from it’s original form. The Stay Puft Test is to demonstrate the effectiveness of the air tight containers' constructed. One marshmallow is placed inside the air tight container and then placed into the vacuum chamber along with another marshmallow.

15 Other Tests performed… Shock/Stress Testing Heat Test Cold Test

16 Integrated Payload

Conclusions Launch the RockSat Geiger counter payload on June 24, 2010 at the NASA WFF. Continue working with students to develop payloads for high altitude balloons and rockets: -Recruit new outstanding graduate and undergraduate students (available $17.5k/yr Master’s degree fellowship). Begin outreach into the physics and engineering of rocket flight to local K-12 schools. Write winning proposals to continue efforts into the future: -NASA EPSCoR Louisiana State Submission - Spring 2010 (subcontractor to Louisiana Tech University - $115k/yr). Continue training students with the motto “walk before you run...”.

Acknowledgements Drs. Greg Guzik and John Wefel at Louisiana State University for all their help in the development of our LaACES and HASP payloads. Other travel and related funding was provided by the State of Louisiana Board of Regents using the Space Grant Program. Colorado Space Grant and RockSat for providing this oppurtunity.

19 Questions???