Physics & Astronomy Colloquium
3:30 PM, Friday, February 28, 2014
Room 155, Chem-Phys Building
Dr. Andrea Pocar
University of Massachusetts Amherst
Neutrinoless double beta decay (0νββ) is a beyond-the-standard-model physics process in which
a nucleus (A,Z) decays to (A,Z+2) with the emission of two electrons (but no neutrinos). Experimental searches
for 0νββ are motivated by the access this process gives to testing any Majorana nature of neutrinos
and lepton number non-conservation. This process is also a sensitive probe of the absolute neutrino mass scale.
EXO (Enriched Xenon Observatory) is an experimental program searching for 0νββ decay of 136Xe.
The first phase of the program, EXO-200, uses 200 kg of Xenon enriched to 80% in 136Xe, liquefied in a
Time Projection Chamber (TPC) with scintillation readout (100 kg active mass), allowing for event calorimetry and 3D
localization of ionizing events. EXO-200 has found the standard two-neutrino decay mode 2νββ of 136Xe,
and has made a precision measurement of the (2.172±0.017[stat]±0.060[sys])×1021yr half.
The collection of both light and charge signals and the reconstruction of event positions for both single
and multi-cluster events allow background discrimination on top of the already low environmental background regime,
and the possibility of studying events with extended topologies. A 5-tonne next generation liquid xenon experiment,
nEXO, based on teh EXO-200 concept while implementing some notable innovations, is currently being designed.
It promises to improve the sensitivity to
improve the sensitivity to 0νββ of 136Xe by ~2 orders of magnitude
and fully access the inverted hierarchy neutrino mass scale. This talk will discuss the
detector performance and recent results from EXO-200 and present the nEXO experiment.
Studying Neutrino Mass with the Enriched Xenon Observatory (EXO)
Refreshments will be served in CP 179 at 3:15 PM