Kent Demien's Summer Research Report

Kent Demien's picture Kent Demien

Carroll College

Dr. Arlene Larabee (now at University of Texas at El Paso)

Supported by NSF-REU

This summer, we explored radiating muon capture (RMC). RMC provides the easiest route to finding the last of the six electroweak constants. This elusive constant, called the pseudoscalar coupling constant, was a tough constant to find and measure. Originally, scientists used ordinary muon capture (OMC) in an attempt to measure the constant. However, this produced numbers with extraordinary errors and so it was clear to scientists that OMC was not the answer.

A muon beam was used at TRIUMF (tri-university meson facility) to smash muons into a cylindrical chamber with different elemental targets. This summer we looked at and analyzed the data for a calcium target. In RMC, the muon would enter the chamber and capture on a calcium nucleus releasing a photon. RMC does not happen very often as compared to OMC (Which happens when a muon is captured and does not release a photon.)

The chamber included four main rings of scintilators to detect particles and photons passing though the area around the target. The rings were labeled A, B, C, and D. Between the B and C ring was a ring of lead called the photon converter. It was so titled because it forced the RMC photons to pair produce into a positron and an electron. The positron and electron could then be tracked through use of the wires in the chamber and the last two circles of scintilators.

The constant depends on the element also. In hydrogen, the constant is the largest and plays the biggest role. By the time that you get down to lead, the constant is nearly zero. Because of its big role in hydrogen, hydrogen is the key element to explore. The paper is being printed right now for the hydrogen version of the constant. The reason it has taken so long to find while Calcium and lead were known years ago, is because the background for hydrogen in this experiment is tremendous. Until the wire chamber model was built, the backgrounds were too large to see any data from the RMC on hydrogen. Now that the chamber has been built, the hydrogen data can be obtained and error is significantly less on the data.

There are many backgrounds that attempt to get in the way of clean data taking. Pion capture looks the same as muon capture so it has to be taken into account. Cosmic rays in the chamber can cause problems. When the muon stops outside of the target, it can release photons that must not be mistaken for RMC photons.

This summer I developed tools needed to work on other elements that have been used as RMC targets. I have written some command files that will make their lives a little easier and FTP'ed some programs and manuals from British Columbia that will make it possible for them to do RMC data analysis. But as far as things that I have done to advance the realm of scientific knowledge, I am afraid that I have fallen quite short this summer.

That is not to say that I haven't learned much this summer. I have learned a lot about quantum mechanical things that I might never have known. I have learned to be patient in learning how to use new software on a completely different computer system. I have been introduced to a new programming language. I am sure that there are many more things that I have learned that I am missing right now, but that will come to me later in life in my studies of physics. Although it was a little disappointing to not be able to advance scientific knowledge even a micron this summer, I still have managed to learn things hat will help me to hopefully advance our understanding later on in my scientific career.

kdemien@carroll1.cc.edu