Characterization of an Characterization of an Antenna for the Search of Antenna for the Search of

Neutrino Mass.Neutrino Mass.By: John NdunguBy: John Ndungu

Advisor: Dr. Leslie RosenbergAdvisor: Dr. Leslie RosenbergPost Doc Advisor: Dr. Gray RybkaPost Doc Advisor: Dr. Gray Rybka

Philander Smith CollegePhilander Smith CollegeUniversity of WashingtonUniversity of WashingtonDepartment of PhysicsDepartment of Physics

Index:Index:

• Intro:Intro:1.1. Neutrinos.Neutrinos.

2.2. Neutrino mass.Neutrino mass.

3.3. Tritium.Tritium.

4.4. Project 8.Project 8.

• Procedure:Procedure:1.1. What is project 8.What is project 8.

2.2. What I built.What I built.

3.3. What was I measuring?What was I measuring?

4.4. How did I do the measurements.How did I do the measurements.

Index:Index:

• Results:Results:1.1. Data.Data.

2.2. Observations.Observations.

• Conclusion:Conclusion:1.1. Unexpected data.Unexpected data.

2.2. Possible causes.Possible causes.

3.3. Future endeavors.Future endeavors.

Neutrinos:Neutrinos:

Small elementary particles theorized Small elementary particles theorized by Wolfgang Pauli in 1930.by Wolfgang Pauli in 1930.

They were once thought to be They were once thought to be massless under the standard model.massless under the standard model.

Extremely abundant (50 trillion solar Extremely abundant (50 trillion solar neutrinos pass through human body neutrinos pass through human body every second).every second).

Neutrino Mass:Neutrino Mass:

Once thought to be massless under Once thought to be massless under the standard model.the standard model.

Due to experiments with neutrino Due to experiments with neutrino flavor oscillations, it was concluded flavor oscillations, it was concluded that they have a mass.that they have a mass.

The current consensus of neutrino The current consensus of neutrino mass states that it is less than 2.7 eV mass states that it is less than 2.7 eV (KATRIN will improve on this figure).(KATRIN will improve on this figure).

1.1. J Bahcall and H Bethe. Phys. Rev. Lett. 65. 2233-2235, 1990.J Bahcall and H Bethe. Phys. Rev. Lett. 65. 2233-2235, 1990.

2.2. R Davis et al Phys. Rev. Lett. 20. 1205-1209, 1968.R Davis et al Phys. Rev. Lett. 20. 1205-1209, 1968.

Tritium:Tritium:

Tritium, also known as Hydrogen-3 is a Tritium, also known as Hydrogen-3 is a radioactive isotope of Hydrogen.radioactive isotope of Hydrogen.

When Tritium beta decays into Helium 3, it When Tritium beta decays into Helium 3, it releases an electron and an electron releases an electron and an electron antineutrino: antineutrino:

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31 eveHeT

Project 8:Project 8:

Purpose of project 8 is to measure Purpose of project 8 is to measure energy of electrons (released in the energy of electrons (released in the decay) in order to determine mass of decay) in order to determine mass of neutrinos.neutrinos.

To do this, we utilize an antenna To do this, we utilize an antenna array that detects electrons trapped array that detects electrons trapped in a solenoid magnet.in a solenoid magnet.

1.1. G Rybka “A Proposal to Detect Single Electrons through their Radiation of Power into a Two-Wire G Rybka “A Proposal to Detect Single Electrons through their Radiation of Power into a Two-Wire

Transmission Line” Project 8 Internal Note 2009.Transmission Line” Project 8 Internal Note 2009.

How project 8 works:How project 8 works:

Tritium gas is Tritium gas is placed in the placed in the middle and allowed middle and allowed to decay.to decay.

Electrons that are Electrons that are released begin to released begin to spin due to the spin due to the magnetic force.magnetic force.

They are then They are then detected by the detected by the antennas.antennas. B Monreal and J Formaggio. “Relativistic Cyclotron B Monreal and J Formaggio. “Relativistic Cyclotron

Radiation Detection of Tritium Decay Electrons as Radiation Detection of Tritium Decay Electrons as a New Technique for Measuring the Neutrino a New Technique for Measuring the Neutrino Mass” 2009. arXiv:0904.2860v1 [nucl-ex].Mass” 2009. arXiv:0904.2860v1 [nucl-ex].

What I builtWhat I built

One of my duties was to create a One of my duties was to create a prototype of the antenna assembly prototype of the antenna assembly using two wires connected to a using two wires connected to a spectrum analyzer.spectrum analyzer.

I would then use a dipole antenna I would then use a dipole antenna (made from a BNC cable) to simulate (made from a BNC cable) to simulate an electron signal.an electron signal.

Device with antenna:Device with antenna:

How I did the measurementsHow I did the measurements

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

Data:Data:

For the most part For the most part the data fit the the data fit the theoretical theoretical function.function.

However it still However it still needs to be needs to be modified as the modified as the wire spacing wire spacing changes (note changes (note bottom pic).bottom pic).

Data @ 2.5 in., spacing 2

Data @ 2.5 in., spacing 1

Data:Data:Data @ 4.5 in., spacing 2

Data @ 6.5 in., spacing 2

Data @ 6.5 in., spacing 1

Data @ 8.5 in., spacing 1

Observations:Observations:

Even though there were a few observable Even though there were a few observable “bumps” in the data, most of it coincided “bumps” in the data, most of it coincided with the theoretical function we derived.with the theoretical function we derived.

The function changes as the method of The function changes as the method of data capturing changes (for ex. P(0)).data capturing changes (for ex. P(0)).

The final function I came up with to fit the The final function I came up with to fit the data was: data was:

49

098402

0285750

0.02857525.0)( 2

22

2

.x-.

xp

Conclusion:Conclusion:

Possible causes for unexpected Possible causes for unexpected data “bumps”:data “bumps”:

1.1. Data was collected in a room with a lot of metal. Could have Data was collected in a room with a lot of metal. Could have reflected stray signals.reflected stray signals.

2.2. Some of the signal could have radiated from coax BNC cable Some of the signal could have radiated from coax BNC cable coating.coating.

3.3. Imperfect dipole and antenna construction.Imperfect dipole and antenna construction.

4.4. Difficulty with position measurements.Difficulty with position measurements.

Future of project 8:Future of project 8:

Some things that I would suggest to Some things that I would suggest to focus on for future project 8 focus on for future project 8 research are:research are:

1.1. Using thinner wires to serve as the antennas.Using thinner wires to serve as the antennas.

2.2. Finding a way to shield the device from stray signals.Finding a way to shield the device from stray signals.

3.3. Finding ways to make the signal reception clearer and Finding ways to make the signal reception clearer and more consistent in order to better derive the power more consistent in order to better derive the power function.function.

Questions?Questions?