Time and location (unless otherwise noted):

Upcoming Colloquium

Tues. 7 May 2024 10 Postponed September, 2024, Prof. Dan Kasen, UC Berkeley / LBNL

Building 50-4-Auditorium



Tues. 4 June 2024, Patrick Feng, Sandia National Laboratory

Building 50-4-Auditorium




Previous Colloquium

Tues. 9 April 2024, Prof. Alberto Ramos Martínez, University of Valencia

Building 50-4-Auditorium

How strong are the strong interactions?

Modern particle physics experiments, e.g. at the Large Hadron Collider (LHC) at CERN, crucially depend on the precise description of the scattering processes in terms of the known fundamental forces. This is limited by our current understanding of the strong nuclear force, as quantified by the strong coupling, S, between quarks and gluons.  Relating S to experiments poses a major challenge as the strong interactions lead to the confinement of quarks and gluons inside hadronic bound states. At high energies, however, the strong interactions become weaker (``asymptotic freedom’’) and thus amenable to an expansion in powers of the coupling.  Attempts to relate both regimes usually rely on modeling of the bound state problem in one way or another.  In this talk I will go over 25 years of theoretical advances that have made possible to determine S without relying on models for the physics at low energies. These techniques, based on Lattice QCD and large scale lattice simulations, are able to produce precise determinations of the strong coupling with negligible theoretical uncertainties. This result will increase the likelihood to uncover small effects of yet unknown physics, and enable stringent precision tests of the Standard Model.

Tues. 12 March 2024, Dr. Larry Phair, LBNL

Building 50-4-Auditorium

Pushing Boundaries: Advancements in Heavy Element Synthesis and Radiation Effects Research at the 88-Inch Cyclotron

The 88-Inch Cyclotron supports ongoing research programs in heavy element studies, nuclear data for societal needs, and technology R&D. Efforts to synthesize elements beyond oganesson (Z=118) will push the limits of current technology due to the expected low production cross sections (below the 100 femtobarn level) and short half-lives (likely of order a few microseconds) for these elements. The approach to making new elements necessitates using beams other than 48Ca. The ion source group at the 88-Inch Cyclotron has developed a Ti beam, which, combined with a Cf target, could produce a new element, Z=120. The Ti beam was created using VENUS and AECR ion sources and new oven technologies. The 88-Inch Cyclotron plans to host a new element search involving long running periods (many months) of intense beams (~1 particle μA 50Ti) on actinide targets to approach the theoretical tens of femtobarn production cross sections. On the applications side, the 88-Inch Cyclotron provides a unique environment for conducting radiation effects testing at the Berkeley Accelerator Space Effects (BASE) Facility, providing well-characterized beams of protons, heavy ions, and other medium energy particles to simulate the space environment. The National Security Space (NSS) community and researchers from other government, university, commercial, and international institutions use these beams to understand the effect of radiation on microelectronics, optics, materials, and cells.

Wed. 7 February 2024, Prof. Filomena Nunes, FRIB/MSU

Building 50A-5132 (Sessler Conference Room)

BAR: Bayesian Analyses of Reactions

Nuclear reactions are an essential probe for studying isotope structure and nuclear astrophysics.

It is from nuclear reactions that we learn about where nuclei come from and how they are produced. Also, reaction experiments provide critical knowledge on how neutrons and protons organize themselves to form matter as we know it and matter at the limits of stability.

However until recently, models for nuclear reactions included no uncertainty quantification. In this presentation, I will review the Bayesian analysis efforts developed over the last 6 years in reaction theory, including not only uncertainty quantification but also steps toward experimental design. This presentation assumes no prior knowledge on Bayesian Statistics.

Some relevant references:

[1] C. Hebborn et al., J. Phys. G 50, 050601 (arXiv:2210.07293)

[2] G.B. King et al., Phys. Rev. Lett. 122, 232502 (2019)

[3] A. Lovell et al., J. Phys. G 48, 014001 (2020)

[4] M. Catacora-Rios et al., Phys. Rev. C 100, 064615 (2019)

[5] T. Whitehead et al., Phys. Rev. C 105, 054611 (2022)

[6] M. Catacora-Rios et al., Phys. Rev. C 108, 024601 (2023)  (arXiv:2212.10698)

[7] M. Catacora-Rios et al., Phys. Rev. C 104, 064611 (2021)

Wed. 10 January 2024, Dr. Annie Kritcher, LLNL

Design of first experiment to achieve fusion target gain > 1

The inertial fusion community have been working towards ignition for decades, since the idea of inertial confinement fusion (ICF) was first proposed by Nuckolls, et al., in 1972. On August 8, 2021 and Dec 5th 2022, the Lawson criterion for ignition was met and more fusion energy was created than laser energy incident on the target at the National Ignition Facility (NIF) in Northern California. The first experiment produced a fusion yield of 1.35 MJ from 1.9 MJ of laser energy and appears to have crossed the tipping-point of thermodynamic instability according to several ignition metrics.  Building on this result, improvements were made to increase the fusion energy output to ~4MJ from 2.05 MJ of laser energy on target, resulting in target gain exceeding unity for the first time in the laboratory.  This result is important in that it proves that there is nothing fundamentally limiting controlled fusion energy gain in the laboratory.  The presentation will detail the changes made to achieve this result.

Bio and photo are attached.