About the INPA Seminars

All seminars are on Fridays (unless otherwise noted) and start at 12:00 (noon) with a brief presentation of the weekly scientific news. Typically the talks end by 13:00. The seminars take place in Bldg. 50A, room 5132.

The committee members are:

The following Seminar schedule for the Institute for Nuclear and Particle Astrophysics is tentative. The seminar becomes final usually a few days before the Friday of the talk.

If you have questions, comments, or suggestions please contact Paris C. Gordon at 510-486-4903 pcgordon@lbl.gov

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Dr. Quentin Riffard (LBL) – Direct detection of Dark Matter: from LUX to LZ

March 1 @ 12:00 pm - 1:00 pm

Liquid xenon two-phase time projection chamber (TPC) is one of the most promising technologies for WIMP dark matter direct detection. By using this technology, the LUX, XENON1T, and PANDAX-II collaborations established the most stringent limits on WIMP-nucleus cross section above 10 GeV. For WIMP searches, the expected signal is composed of nuclear recoils (NR), while our background is composed by both electron recoils (ER) and NR. The limits on the WIMP-nucleus cross section are extracted using a Profile Likelihood Ratio (PLR). The usage of the PLR requires a precise knowledge of signal and background models. In the first section, I will focus on the improvement of the detector response modeling and the re-analysis of the background model for LUX Run4 analyses. The LUX Run4 represents a challenge for the modeling of the detector response as several experimental parameters vary as a function of time. Then I will present a new detector response model based on the NEST yield model to consider those variations. This new model has been tuned on Run4 calibration data across many electric fields. After the decommissioning of the LUX experiment, some parts of the detector have been re-assayed to reevaluate the activity of the contaminants. I’m developing a new background model based on a Monte-Carlo simulation of the detector and those new measurements. Once achieved, this background model will be used in future analyses. I used the new detector response model to test the impact of the electric field and the light collection efficiency on detector sensitivity for several dark matter models.

Among few collaborations, the LUX-ZEPLIN (LZ) is currently building one of the next generation of dark matter detector. The NR response detector calibration is a fundamental aspect of dark matter searches. I am involved in development of a photo-neutron source for the low energy NR calibration of the detector. By using a Monte-Carlo simulation, we determined the expected event rate. Moreover, by using photo neutron simulations, I also identify a plausible low energy calibration source. After Xe neutron capture, we have the emission of very high energy gammas ~ 9 MeV and a ~300 eV NR. In some case only the NR is visible as the gamma can escape the LXe without depositing any energy. By using the veto to tag this neutron capture reaction, I show that we have a new possible low energy NR internal calibration source.


March 1
12:00 pm - 1:00 pm


Sessler Conference Room CA

INPA guests from campus can now come up to the lab early on Fridays. The INPA Common Room (50-5026) is reserved for our guests from 10:00 am to 12:00 noon, and from 1 pm to 5 pm. Note that the seminars are now held in 50A-5132 to accommodate a larger number of attendees.

Also, on Fridays from 1:00 pm to 2:00 pm you are welcome to join the INPA Speaker for a brown-bag lunch in the small Pers Hall conference room, 54-130B.

INPA Tea Series

The Physics and Nuclear Science Divisions have together been leaders in revolutionary changes in our understanding of neutrinos and cosmology. Everyone is welcome to attend the open forum. Tea and light refreshments will be served.

INPA Common Room (50-5026)
3:30 pm

Access to the Lab

For a shuttle pass please email Paris C. Gordon. Please note: the pass is only valid for the day of the seminar.

If you have questions, comments, or suggestions please contact, preferably via email, Paris C. Gordon.