Characterization of an Antenna for the Search of Neutrino Mass.

1. Characterization of an Antenna for the Search of Neutrino Mass. By: John Ndungu Advisor: Dr. Leslie Rosenberg Post Doc Advisor: Dr. Gray Rybka Philander Smith College University of Washington Department of Physics

2. Index: • Intro: • Neutrinos. • Neutrino mass. • Tritium. • Project 8. • Procedure: • What is project 8. • What I built. • What was I measuring? • How did I do the measurements.

3. Index: • Results: • Data. • Observations. • Conclusion: • Unexpected data. • Possible causes. • Future endeavors.

4. Neutrinos: • Small elementary particles theorized by Wolfgang Pauli in 1930. • They were once thought to be massless under the standard model. • Extremely abundant (50 trillion solar neutrinos pass through human body every second).

5. Neutrino Mass: • Once thought to be massless under the standard model. • Due to experiments with neutrino flavor oscillations, it was concluded that they have a mass. • The current consensus of neutrino mass states that it is less than 2.7 eV (KATRIN will improve on this figure). • J Bahcall and H Bethe. Phys. Rev. Lett. 65. 2233-2235, 1990. • R Davis et al Phys. Rev. Lett. 20. 1205-1209, 1968.

6. Tritium: • Tritium, also known as Hydrogen-3 is a radioactive isotope of Hydrogen. • When Tritium beta decays into Helium 3, it releases an electron and an electron antineutrino:

7. Project 8: • Purpose of project 8 is to measure energy of electrons (released in the decay) in order to determine mass of neutrinos. • To do this, we utilize an antenna array that detects electrons trapped in a solenoid magnet. G Rybka “A Proposal to Detect Single Electrons through their Radiation of Power into a Two-Wire Transmission Line” Project 8 Internal Note 2009.

8. How project 8 works: • Tritium gas is placed in the middle and allowed to decay. • Electrons that are released begin to spin due to the magnetic force. • They are then detected by the antennas. B Monreal and J Formaggio. “Relativistic Cyclotron Radiation Detection of Tritium Decay Electrons as a New Technique for Measuring the Neutrino Mass” 2009. arXiv:0904.2860v1 [nucl-ex].

9. What I built • One of my duties was to create a prototype of the antenna assembly using two wires connected to a spectrum analyzer. • I would then use a dipole antenna (made from a BNC cable) to simulate an electron signal.

10. Device with antenna:

11. How I did the measurements • I split the cavity into several zones according to the length of the wire and the height of the position of the antenna (with respect to the two wires).

12. Data: Data @ 2.5 in., spacing 2 • For the most part the data fit the theoretical function. • However it still needs to be modified as the wire spacing changes (note bottom pic). Data @ 2.5 in., spacing 1

13. Data: Data @ 6.5 in., spacing 1 Data @ 4.5 in., spacing 2 Data @ 6.5 in., spacing 2 Data @ 8.5 in., spacing 1

14. Observations: • Even though there were a few observable “bumps” in the data, most of it coincided with the theoretical function we derived. • The function changes as the method of data capturing changes (for ex. P(0)). • The final function I came up with to fit the data was:

15. Conclusion: • Possible causes for unexpected data “bumps”: • Data was collected in a room with a lot of metal. Could have reflected stray signals. • Some of the signal could have radiated from coax BNC cable coating. • Imperfect dipole and antenna construction. • Difficulty with position measurements.

16. Future of project 8: • Some things that I would suggest to focus on for future project 8 research are: • Using thinner wires to serve as the antennas. • Finding a way to shield the device from stray signals. • Finding ways to make the signal reception clearer and more consistent in order to better derive the power function.

17. Questions?