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, suggestions or like to be added to the INPA News mailing list please contact Paris Gordon at 510-486-4903 [email protected]

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Virtual INPA SEMINAR| Nguyen Phan (LANL)

January 15 @ 10:00 am - 11:00 am

Speaker: Nguyen Phan (Los Alamos National Laboratory) 

Title: “Understanding Electrical Breakdown in Liquid Helium through Analysis of the Empirical Breakdown Field Distributions”


Many present and future large-scale detectors in nuclear, particle, and astroparticle physics experiments will employ very high voltages and/or high electric fields inside a noble liquid detection medium.  However, electrical breakdown in these dielectric materials is still poorly understood and may pose a challenge to the design and operation of such experiments.  The neutron electric dipole moment (nEDM) experiment currently being developed to be mounted at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory will perform its measurements in superfluid helium with a target field of 75 kV/cm.  Vital to achieving such a high field at large-scale is a better understanding of the breakdown phenomenon.  To that end, we have collected data on the distribution of the breakdown voltages for small stainless steel electrodes with different surface polishes immersed in liquid helium, at various temperature and pressures, with the goal of providing guidance on the design of the high voltage system for the nEDM experiment at SNS, but also with potential application to other noble liquid experiments.  In this talk, we will show how a statistical analysis of our data can be used to determine the electrode surface area scaling of the breakdown field, a behavior that is of central importance to the design of large-scale detectors employing high voltage.  We will show that the dependence of the probability of breakdown on the field strength, extracted from the data, closely resembles that of the field emission, giving a strong indication that the initial process involves the field emission from the cathode.  A method to optimize the design of arbitrary-shaped electrodes to reduce the risk of breakdown is also presented.  Most importantly, the methods proposed in this work can be extended to other noble liquids to explore the behavior of electrical breakdown in those media.

Join Zoom Meeting


Meeting ID: 937 5807 0002

Passcode: 876187


January 15
10:00 am - 11:00 am

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 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 Gordon.