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DTSTAMP:20261020T233850Z
LAST-MODIFIED:20151014T153924Z
DTSTART:20151019T170000Z
DTEND:20151019T180000Z
UID:event1496@bu.edu
URL:http://physics.bu.edu/internal/events/show/1496
SUMMARY:A Precision Measurement of the Rate of Muon Capture on the Deuteron
DESCRIPTION:Featuring Xiao Luo\n\nPart of the PhD Final Oral Exams.\n\nDiss
	ertation Committee:  Robert Carey\, James Miller\, John Butler\, So-Young P
	i\, Shyam Erramilli\n\n\nABSTRACT\nBecause quantum chromodynamics (QCD) is 
	non-perturbative at low energies\, strong interactions\nat the ⇠ GeV scal
	e are very challenging to understand. Theoretical progress\nhas been made r
	ecently using QCD-based e↵ective field theories (EFT). The short-distance
	\nphysics of the e↵ective theory is absorbed into a limited number of low
	 energy constants\n(LECs)\, which are determined by direct experimental mea
	surement. The MuSun experiment\nis measuring the rate ⇤d for muon capture
	 on the deuteron\, which is the simplest weak\ninteraction in a two nucleon
	 system. ⇤d will be used\, in turn\, to better determine a fundamental\nL
	EC known as dR in the EFT. An improvement in the precision of this LEC will
	\nimprove our understanding of several other processes in the two-nucleon s
	ector: pp fusion\,\nthe main source of energy in the sun and other main-seq
	uence stars and neutrino-deuteron\nscattering\, as observed in the SNO expe
	riment.\n\nThe MuSun experiment determines ⇤d via a precision measurement
	 of the negative\nmuon lifetime in deuterium. The time di↵erence between 
	an incoming muon\, which stops\nin deuterium\, and the subsequent decay ele
	ctron characterizes the muon disappearance rate.\nThat disappearance rate i
	s the sum of the ordinary muon decay rate and the nuclear capture\nrate. Th
	e ultimate goal of the MuSun experiment is to determine the nuclear capture
	 rate\n(⇤d) to a precision of 1.5 %\, an order of magnitude improvement o
	ver previous e↵orts.\nThe principal experimental development required to 
	achieve this goal is a cryogenic (T ⇠30\nK) time projection chamber\, whi
	ch not only serves as the deuterium gas target\, but also\nprovides an unam
	biguous measurement of muon stopping position - muons that stop in high\nZ 
	materials outside the fiducial deuterium volume produce a very large system
	atic error.\nThe low temperature helps minimize several other systematic er
	rors.\n\nThe MuSun experiment is taking place at the Paul Scherrer Institut
	 in Villigen\, Switzerland.\nOver the past 5 years\, the MuSun collaboratio
	n has staged 4 major experimental\nproduction runs. In this thesis\, I pres
	ent a measurement of the muon capture rate on deuterium\,\nas determined fr
	om data taken in the summer of 2013. The estimated statistical\nand systema
	tic error is about 7.5%.\n\n![Xiao](/resources/event-image/1496/8dbdbf8_ori
	ginal)
LOCATION:PRB 365\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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