You are here

Upcoming Seminars & Lectures

DateTime SpeakerLocationTitle
14:00AcceleratorStudents/Postdocs presenting at IPAC'18
ISAC II Conf RmPractice Session for IPAC'18 Poster Session
Abstract:Postdocs and students will give a brief presentation of their IPAC'18 posters.
Fri ,
14:30SpecialPSD Mixer
AuditoriumPhysical Sciences Division Mixer
Abstract:Jens Dilling - Division Updates (10 minutes); Q&A with Jens (10 minutes); Talk by Adam Garnsworthy (20 minutes); Adam Garnsworthy (TRIUMF) "Powers of Two" The GRIFFIN spectrometer at TRIUMF-ISAC was specifically designed with high gamma-ray efficiency and high granularity in order to achieve an impressive coincidence efficiency which is a factor of 300 larger than its predecessor, the 8pi spectrometer. I will give an introduction to the advanced gamma-ray spectroscopy techniques such as gamma-gamma angular correlations and Compton polarimetry that are only possible when two or more gamma rays are detected at the same time. We will look at examples of the detailed investigations that are now possible in order to elucidate the structure of atomic nuclei.
Thu ,
14:00ColloquiumIan Roederer
University of Michigan
AuditoriumThe astrophysical r-process: What we are learning from gravitational waves, dwarf galaxies, and stellar archaeology
Abstract:Understanding the origin of the elements is one of the major challenges of modern astrophysics. The rapid neutron-capture process, or r-process, is one of the fundamental ways that stars produce the elements listed along the bottom 2/3 of the periodic table, but key aspects of the r-process are still poorly understood. I will describe three major advances in the last few years that have succeeded in confirming neutron star mergers as an important site of the r-process. These include the detection of freshly produced r-process material powering the kilonova associated with the merger of neutron stars detected via gravitational waves (GW170817), the detection of a dwarf galaxy where most of the stars are highly enhanced in r-process elements (Reticulum II), and advances in deriving abundances of previously-undetected r-process elements (Se, Te, Pt) in ultraviolet and optical spectra of metal-poor stars in the Milky Way halo field. I will describe future prospects that connect these three research directions and future rare isotope accelerators to associate specific physics with specific sites of the r-process.
Mon ,
14:00SpecialPaul Lecoq
AuditoriumThe 10ps TOFPET Challenge, Myth or Reality
Abstract:The future generation of radiation detectors is more and more demanding on timing performance for a wide range of applications, such as time of flight (TOF) techniques for PET cameras and particle identification in nuclear physics and high energy physics detectors, precise event time tagging in high luminosity accelerators and a number of photonic applications based on single photon detection. A target of 10ps coincidence time resolution in TOFPET scanners would introduce a paradigm shift in PET imaging. Besides resulting in on-line image formation, the localisation of annihilation events directly from their TOF provides ultimate use of the dose delivered to the patient to get the best Signal to Noise Ratio into the resulting image and offers a potential reduction of the scan duration and a direct access to the image during the scan itself. Reconstructionless TOF-PET also reduces efficiently undesired effects inherent to the PET detection, namely randoms and scatters when appropriately correlated to energy discrimination, hence contributing to reduce dose, scan duration and possibly scan cost while using very short-lived positron emitting isotopes. The time resolution of a scintillator-based detector is directly driven by the density of photoelectrons generated in the photodetector at the detection threshold. At the scintillator level it is related to the intrinsic light yield, the pulse shape (rise time and decay time) and the light transport from the gamma-ray conversion point to the photodetector. When aiming at 10ps time resolution fluctuations in the thermalization and relaxation time of hot electrons and holes generated by the interaction of ionization radiation with the crystal become important. This talk will review the different processes at work and evaluate if some of the transient phenomena taking place during the fast thermalization phase can be exploited to extract a time tag with a precision in the few ps range. Some considerations will also be given on the possibility to exploit quantum confinement for the production of ultrafast spontaneous or stimulated emission in semi-conductors. The light transport in the crystal is also an important source of time jitter. In particular light bouncing within the scintillator must be reduced as much as possible as it spreads the arrival time of photons on the photodetector and strongly reduces the light output by increasing the effect of light absorption within the crystal. A possible solution to overcome these problems is to improve the light extraction efficiency at the first hit of the photons on the crystal/photodetector coupling face by means of photonic crystals (PhCs) specifically designed to couple light propagation modes inside and outside the crystal at the limit of the total reflection angle. Finally the present limitations of the photodetectors, and in particular the SiPMs will be discussed and some R&D lines to meet the 10ps challenge will be presented.
Thu ,
14:00ColloquiumMartin Fertl
U Washington
AuditoriumProject 8: A frequency-based approach to measure the absolute neutrino mass scale
Abstract:Neutrino flavor oscillation experiments prove that neutrinos do have nonzero masses. Extensions to the Standard Model of Particle Physics have been developed to explain the non-zero masses and can be directly tested by a measurement of the absolute neutrino mass scale. The mass of the electron antineutrino can be determined from the highest precision measurement of the beta-decay spectrum of tritium around its endpoint region (Q = 18.6 keV). The current state of the art experiment stretches all technological limits to probe the range of the electron antineutrino mass down to 200meV. A completely new path has to be envisioned to test the full range of electron neutrino masses allowed in the inverted neutrino mass ordering scheme. The Project 8 collaboration has recently demonstrated the novel technique of Cyclotron Radiation Emission Spectroscopy (CRES) to pursue a frequency-based measurement approach. I will present this new approach and results obtained with mono-energetic conversion electrons from 83m^Kr. The phased program towards a measurement using atomic tritium with a mass sensitivity potentially below 40meV will be discussed as well as the application of CRES to high energy beta-decays in searches for exotic, tensor-like interactions. Financial support by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics to the University of Washington under Award Number DE-FG02-97ER41020 is acknowledged.
Mon ,
12:15Particle Phys/SciTecSophie Berkman
Auditoriumνμ CC1π+ Events Produced in the T2K Beam at Super-Kamiokande
Thu ,
14:00ColloquiumSandrine Huclier
Subatech IN2P3
AuditoriumStatus of Medical (Theragnostic) Radionuclide Production at the Arronax Facility
Tue ,
13:00TheoryGopolang Mohlabeng
Brookhaven National Laboratory
AuditoriumRevisiting the Dark Photon Interpretation of the Muon g-2 anomaly
Abstract:We investigate the parameter space in which the dark photon may still explain the muon g-2 anomaly. We consider a model of an inelastic dark sector which couples directly to the dark photon. This scenario may lead to semi-visible decays of the dark photon leading to a parameter space in which the dark photon interpretation of the muon g-2 anomaly may still be viable as opposed to both exclusively visible and invisible decays, which have been excluded by experiments. Furthermore, we show that one of the dark sector states may contribute to the required dark matter relic abundance. It is possible that the semi-visible events we discuss, may have been vetoed by experiments searching for the invisible dark photon decays, such as BABAR.