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Lunchtime Seminars

Tuesdays ~ 12pm ~ Kolker Room, 26-414

 

Committee:
Gunther Roland, Chair ~ Doug Hasell~ Paolo Zuccon



March 17, 2015

 

Ben Jones

Dynamical Pion Collapse and the Coherence of Neutrino Beams

Neutrino oscillations are very clear evidence of phenomena beyond the standard model, and measuring the parameters which govern them is a major area of current research. The textbook theoretical treatment of neutrino oscillations, however, is known to be both approximate and inconsistent. The range of its validity is debated, with some estimates suggesting that neutrino coherence loss due to wavepacket separation can occur in existing experiments. This would fundamentally change neutrino oscillation phenomenology, especially if heavier, sterile neutrinos participate in the oscillation. All calculations of these effects to date require an assumption about the initial neutrino state, usually obtained by dimensional analysis, and spanning several orders of magnitude between treatments. In this talk I will show that derivation of neutrino coherence properties without an arbitrary initial-state assumption is possible if the neutrino beam is properly treated as an open quantum system. I will present the first such calculation, where the full oscillation phenomenology of neutrinos produced in accelerator neutrino beams is derived without arbitrary spatial scales at the neutrino production vertex. The resulting range of validity of the typical neutrino oscillation formalism will then be discussed.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)


March 24, 2015

No Seminar

Spring Break



March 31, 2015

No Seminar


 

April 7, 2015

 

Antonia Hubbard

Muon-Induced Backgrounds in DM-Ice NaI(Tl) Dark Matter Detectors

Ice is a NaI(Tl) experiment searching for an annually-modulating dark matter signal. The DM-Ice17 detector has successfully operated in the South Pole ice for three years, and R&D efforts for the full-scale detector are underway at FNAL and the Boulby Underground Laboratory. I present an analysis of the muon background in DM-Ice, including long-lived phosphorescence observed in both DM-Ice17 and DM-Ice37. The DM-Ice17 muon analysis also includes events that are coincident with IceCube. The expected annual modulation in the rate of muons is observed.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)


 

April 14, 2015

 

Kyungeun E. Lim, Yale University

Results from the Search for Neutrinoless Double-Beta Decay in the Te-130 with CUORE-0

CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of Te-130. The detector consists of 52 TeO2 crystal bolometers held in a ultra-pure copper frame and it was assembled using the new low-background techniques developed for CUORE. Using bolometers operated at ∼ 10 mK provides excellent energy resolution (< 0.2% FWHM) at the neutrinoless double-beta decay Q-value. CUORE-0 is located at the Laboratori Nazionali del Gran Sasso in Italy and has been taking data since March 2013. I will present the experiment and its neutrinoless double- beta decay search results with a 9.8 kg·yr exposure of Te-130. I will also discuss the prospects of CUORE, which has a Te-130 mass 19 times greater than that of CUORE-0. CUORE is in the final stages of the construction and scheduled to begin data-taking in late 2015.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)


 

April 21, 2015

 

Makoto C. Fujiwara, TRIUMF

Casting Light on Antimatter: Fundamental Physics with the ALPHA Antihydrogen Trap

ALPHA is an international project at CERN, whose ultimate goal is to test symmetry between matter and antimatter, such as CPT invariance and the Weak Equivalence Principle, via precision studies of atomic antihydrogen. After several years of development, we have recently achieved significant milestones: stable confinement of antihydrogen [1], for as long as 1000 seconds [2]. ALPHA has also succeeded in performing the first proof-of-principle spectroscopic measurement on antihydrogen atoms by driving their hyperfine transitions with microwaves [3]. Furthermore, we reported a precision measurement of charge neutrality of antihydrogen [4], which in turn provides an improved measurement of the electric charge of the positron, as a test of CPT.

 

Following these milestones, we have constructed an entirely new apparatus, ALPHA-2. It allows laser access to the trapped anti-atoms, enabling laser cooling and precision spectroscopy. ALPHA-2 was successfully commissioned in late 2014, and the physics run is starting this summer. For the longer-term, possibilities for measurements of the antimatter-gravity interaction are being explored with a proposed project, ALPHA-g. In this talk, I will start with some discussions of the motivations [5], followed by recent achievements and the future prospects of fundamental physics studies with ALPHA.

 

References : [1] G. B. Andresen et al., Nature 468, 673 (2010). [2] G.B. Andresen et al., Nature Physics 7, 558 (2011). [3] C. Amole et al., Nature 483, 439 (2012). [4] C. Amole et al. Nature Communications 5, 3955 (2014). [5] M.C. Fujiwara, Antihydrogen, CPT, and Naturalness, arXiv:1309.7468.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)

 


 

April 28, 2015

 

Taritree Wongjirad

A New Short-Baseline Muon-Neutrino Disappearance Experiment using Neutrinos from Kaon Decay-at-rest

Recently, anomalies consistent with neutrino oscillations with mass splittings on the order of 1 eV2 have been observed. These anomalies have been seen in experiments measuring nue appearance and nue/nue-bar disappearance, while no corresponding evidence for muon neutrino disappearance has been detected. A common interpretation of the anomalies involves postulating the existence of one or more "sterile" neutrinos that, unlike the three Standard Model neutrinos, do not interact via the electroweak force. While models with sterile neutrinos can explain the current data, they all require that some amount of muon neutrino disappearance must occur, with several models indicating that evidence for the process might have been just below the sensitivities of past experiments. In this talk, I present a new type of experiment that will search for muon neutrino disappearance at the Materials and Life Science Facility (MLF), which is a part of the JPARC accelerator complex in Tokai, Japan. The facility features a high intensity, pulsed beam of 3 GeV protons used to produce neutron, muons, and neutrinos for various experiments. In our proposal, we would measure mono-energetic neutrinos coming from kaon decay-at-rest with a detector consisting of a 3 m diameter by 90 m long pipe filled with liquid scintillator. This setup would aim to measure directly the L/E oscillation wave in the event rate along the length of the detector. Such a signal would provide convincing evidence for a sterile neutrino and avoids some of the difficulties in past experiments in characterizing the incoming neutrino flux and modeling neutrino-nucleus interaction cross sections.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)


 

May 5, 2015

 

James Maxwell, M.I.T.

The SNS Measurement of the Neutron Electric Dipole Moment

The advancing precision of measurements of the neutron’s electric dipole moment (nEDM) offers a crucial view into Physics beyond the Standard Model. An experiment planned for the fundamental neutron physics beamline at Oak Ridge National Laboratory’s spallation neutron source aims to reduce the uncertainty in nEDM to 10-28 e*cm, two orders of magnitude beyond the present limit. We will discuss the motivation and method of this effort, and detail the status of the challenging technical developments that are required to reach the desired precision.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)



May 12, 2015

No Seminar


 

May 19, 2015

 

Alex Zylstra, M.I.T. PSFC*

Studies of 3He+3He, T+3He, and p+D nuclear reactions, relevant to stellar and Big-Bang Nucleosynthesis, using inertially-confined plasmas

The 3He+3He, T+3He, and p+D reactions directly relevant to Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using high-temperature inertially-confined plasmas. These plasmas are generated by laser-driven spherical implosion. The advantage of using these thermal plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments, and nuclear diagnostics developed for inertial fusion applications can be employed. Proton spectra from the 3He+3He reaction, final step of the stellar proton-proton I chain, were measured for the first time in a plasma, and are used to constrain nuclear R-matrix modeling. Recent experiments have probed the p+D reaction for the first time in a plasma; this reaction is relevant to energy production in protostars, brown dwarfs and, at higher CM energies, to BBN. The plasma data are used to calculate an S-factor, which agrees with prior accelerator data; this is the first direct comparison of plasma and accelerator data for a reaction relevant to astrophysics. Lastly, the T+3He reaction was studied, with charged particles and g rays from several reactions branches measured. The proton spectrum from the T+3He reaction is also being used to constrain the R-matrix model. The resulting T+3He g-ray data rule out an anomalously-high 6Li production during the Big Bang as an explanation to the high observed values in metal poor first generation stars.

 

*This work was done as part of a Ph.D. thesis, and was supported in part by DoE, NNSA, NSF, LLNL, LLE, and LANL

 

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served.)