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 Nuclear Tuesday, January 24, 2017 3:30 PM Physics Building, Room 204 "Available" Nuclear Tuesday, January 31, 2017 3:30 PM Physics Building, Room 204 "Available" Nuclear Tuesday, February 7, 2017 3:30 PM Physics Building, Room 204 Reserved - Please see the Colloquia Schedule Nuclear Tuesday, February 14, 2017 3:30 PM Physics Building, Room 204 "Available" Nuclear Tuesday, February 21, 2017 3:30 PM Physics Building, Room 204 "Available" Nuclear Tuesday, February 28, 2017 3:30 PM Physics Building, Room 204 Reserved - Please see the Colloquia schedule Nuclear Tuesday, March 14, 2017 3:30 PM Physics Building, Room 204 Danning Di [Host: Nilanga Liyanage] UVA- Department of Physics "GEM detectors for new generation nucleon form factor experiments in Hall A at JLab" ABSTRACT:The electromagnetic form factors of the nucleon are essential for our understanding of the structure of the nucleon. Precision measurements of nucleon form factors is a fundamental part the Je erson Lab experimental program. The 12 GeV beam upgrade and the newly designed Super BigBite Spectrometer make possible a new generation of experiments to measure nucleon form factors with high precision at high Q2 values around 10 GeV2. The concept of the Super BigBite Spectrometer, which provides large solid angle and the capability to operate at  high luminosity, is based on new Gas Electron Multiplier (GEM) detector based particle trackers. The SBS GEM chambers are expected to provides a good position resolution of 70 m, while operating in high rate conditions up to 0.5 MHz=mm2. A set of 40 GEM detectors, each with an active area of 60x50 cm2, has been built in the GEM detector lab at UVa for the the proton polarimeter trackers of SBS. This seminar will present an overview of SBS nucleon form factor experiments and will report on the Research, development and testing of SBS GEM chamber data acquisition system which is essential to make those high rate experiments possible. Nuclear Tuesday, March 21, 2017 3:30 PM Physics Building, Room 204 Dat Duong [Host: Bob Hirosky] UVA-Physics "Dark Astronomical Compact Object (DACO) and its implications"   Slideshow (PDF) ABSTRACT:Strongly self-interacting dark matter (SSIDM) was proposed as a candidate which might be able to solve astrophysical problems plaguing collisionless cold dark matter: the cusp-vs-core, the missing satellite and the too-big-to-fail problems. These SSIDM particles can in principle form bound states. In particular, if the SSIDM particles belong to a confining gauge group, the singlet states (similar to the baryons of QCD but whose spin depends on the gauge group), the so-called dark "baryons", can cluster into astronomical compact objects which will be called Dark Astronomical Extreme Compact Objects (DAECO) in this paper. How massive can they be? What are their typical sizes? Depending on the mass of the dark baryon, a DAECO can be as "large" as 33 Earth mass for a 1-TeV dark baryon to 0.3 Earth mass for a 10-TeV dark baryon. These DAECOs are extremely small: 15 cm for the 33-Earth mass DAECO and 1.5 mm for the 0.3-Earth mass one. These planetary-mass-type DAECO’S could be "detected" for using techniques such as the astrometric measurements as applied to the searches for exoplanets. Specifically, one would look for gravitational influences of DAECOS’s on a given star when they come close to it. The search for DAECO’s, if they exist, would provide a "direct" detection of strongly self-interacting dark matter at an astronomical level, somewhat similar to laboratory direct detection searches through the detection of nuclear recoil. Another possibility is the merger of two clusters of DAECOs with each having a mass ∼ 30 M generating gravitational waves of the types observed by LIGO. SLIDESHOW: Nuclear Tuesday, March 28, 2017 3:30 PM Physics Building, Room 204 Raphael Dupre [Host: Simonetta Liuti] Institut de Physique Nucléaire d'Orsay "Recent Results on Hadron Tomography using the Generalized Parton Distributions" Nuclear Tuesday, April 4, 2017 3:30 PM Physics Building, Room 204 RESERVED Condensed Matter Tuesday, April 11, 2017 3:30 PM Physics Building, Room 204 Chunruo Duan [Host: Despina Louca] "The Effects of Annealing on Fe Vacancy and Superconductivity in K_xFe_{2-y}Se_2" ABSTRACT:The unique Fe vacancy ordering in alkali metal doped iron selenide $$A_xFe_{2-y}Se_2$$ (A=K, Rb, Cs, $$\cdots$$) has drawn a lot of attention among the Fe-based superconductor community. In this work we investigated the effects of annealing on Fe vacancy in $$K_xFe_{2-y}Se_2$$ single crystal samples by high energy X-ray diffraction and Monte Carlo simulation. The X-ray results indicated that the I4/mmm phase volume fraction decreased after annealing, while the simulation results demonstrated that this shrink of I4/mmm phase is accompanied with a expand of the Fe vacancy disordered area at the domain boundaries. Together with the well known annealing induced superconductivity enhancement, we found that superconductivity in this system is most likely related to the Fe vacancy disordered region. Nuclear Tuesday, April 18, 2017 3:30 PM Physics Building, Room 204 Xinzhan Bai [Host: Nilanga Liyanage] UVA- Physics Department "PRad experiment at Jefferson Lab" Nuclear Tuesday, April 25, 2017 3:30 PM Physics Building, Room 204 Dan Abrams [Host: Donal Day] UVA-Physics "TBA" Nuclear Tuesday, May 2, 2017 3:30 PM Physics Building, Room 204 RESERVED