Joel Sander

Position

Postdoctoral Scholar

Education:

Current Occupation

I am currently leading the day-to-day testing under Professor Harry Nelson of a novel prototype neutron detector. (Here is a link showing an older design.) This neutron detector will measure the high energy neutron flux in deep underground sites. The high energy neutrons, which are produced by muon interactions in the surrounding rock, are highly vertical and produce hadronic showers in the lead. A neutron freed in a shower can wander back into the scintillator where it is moderated down in energy by elastic scattering off of hydrogen until it is captured on a Gadolinium atom. The characteristic time for the neutron to be captures is about 30μs.

Since graduating, I have been testing a prototype vessel that is designed to observe the captures of neutrons, μK. We call this vessel μK because it is filled with water and is about a millionth the size of SuperK. (Water is cheaper than liquid scintillator and easier to safely handle in a mine, but doesn't produce as much Cherenkov light.) The Cherenkov light produced by a neutron capture is observed by 2 PMTs. Here is a picture of μK. μK is an acrylic cylinder (approximately 60cm tall and 20cm diameter) with a layer of aluminized Mylar wrapped around it residing within a light-tight box.

We have been able calibrate μK in several ways including triggering on vertical muons passing directly through μK and by measuring the single photo-electron peak produced by feeding the light from a blue LED into μK through an optical fiber. We have also been able to observe neutrons from a Cf-252 source placed inside μK.

Currently, we are building a much improved prototype that we hope to deploy in the Soudan Underground Laboratory late this summer.

Graduate Work

My graduate work was on an experiment (the Cryogenic Dark Matter Search or CDMS) attempting to directly detect a candidate dark matter particle (the Weakly Interacting Massive Particle or WIMP) in a detector in the Soudan Underground Laboratory located 2341ft (2000mwe) underground. You can read more about CDMS on our Berkeley homepage or in my thesis which can be found from the "Dissertations" link on the Berkeley homepage.

Address

	   Office: 5302 Broida Hall
             Mail: Physics Department
                   University of California
                   Santa Barbara, CA 93106-9530
            Phone: (805)893-7218
              FAX: (805)893-8597
           E-Mail: joel at hep.ucsb.edu

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