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Open Access Publications from the University of California

Physics Department

UC Santa Cruz

About

The Physics Department is made up of twenty-four faculty members, who conduct research in the areas of condensed matter (theory and experiment), particle physics (theory and experiment), biophysics, and astrophysics and cosmology.  We are home to some of the most creative faculty and unique research programs in the nation.  As individuals, our faculty members have received numerous awards.

In a report by the Institute for Scientific Information, UCSC Physics' professional papers had the highest citation rate of any university physics department in the country. With a strong condensed matter physics group and with our close connection to the Santa Cruz Institute for Particle Physics (SCIPP) and scientific associations with Stanford Linear Accelerator Center (SLAC) and Stanford Synchrotron Radiation Laboratory (SSRL) at Stanford, the UC Observatories, and various x-ray and neutron scattering centers at national laboratories we continue to provide exceptional research opportunities to our students.

Our graduate students work closely with our faculty to develop and conduct original research. Coursework provides a depth of knowledge in the student's main areas of interest, as well as breadth in physics.

We offer the following the following three undergraduate majors: Physics, Physics (Astrophysics), and Applied Physics.  Each shares the same rigorous core of lower and upper division courses, with the differences appearing primarily in the upper-division electives chosen. Highly motivated students also have the opportunity to work as research assistants with our faculty.

We also have active postdoctoral researchers in the department, who are extending their research skills, in conjunction with our faculty.

We hope you enjoy learning more about our department as you visit our web site.  

Physics Department

There are 1657 publications in this collection, published between 1962 and 2024.
Open Access Policy Deposits (1657)

Measurement of the inclusive cross-sections of single top-quark and top-antiquark t-channel production in pp collisions at s=13 TeV with the ATLAS detector

A measurement of the t-channel single-top-quark and single-top-antiquark production cross-sections in the lepton+jets channel is presented, using 3.2 fb−1 of proton-proton collision data at a centre-of-mass energy of 13 TeV, recorded with the ATLAS detector at the LHC in 2015. Events are selected by requiring one charged lepton (electron or muon), missing transverse momentum, and two jets with high transverse momentum, exactly one of which is required to be b-tagged. Using a binned maximum-likelihood fit to the discriminant distribution of a neural network, the cross-sections are determined to be σ(tq) = 156 ± 5 (stat.) ± 27 (syst.) ± 3 (lumi.) pb for single top-quark production and σ(t¯ q) = 91 ± 4 (stat.) ± 18 (syst.) ± 2 (lumi.) pb for single top-antiquark production, assuming a top-quark mass of 172.5 GeV. The cross-section ratio is measured to be Rt=σ(tq)/σ(t¯q)=1.72±0.09 (stat.) ± 0.18 (syst.). All results are in agreement with Standard Model predictions.[Figure not available: see fulltext.]

Origin of the tentative AMS antihelium events

We demonstrate that the tentative detection of a few antihelium events with the Alpha Magnetic Spectrometer (AMS) on board the International Space Station can, in principle, be ascribed to the annihilation or decay of Galactic dark matter, when accounting for uncertainties in the coalescence process leading to the formation of antinuclei. We show that the predicted antiproton rate, assuming the antihelium events came from dark matter, is marginally consistent with AMS data, as is the antideuteron rate with current available constraints. We argue that a dark matter origin can be tested with better constraints on the coalescence process, better control of misidentified events, and with future antideuteron data.

Particle-Tracking Proton Computed Tomography—Data Acquisition, Preprocessing, and Preconditioning

Proton CT (pCT) is a promising new imaging technique that can reconstruct relative stopping power (RSP) more accurately than x-ray CT in each cubic millimeter voxel of the patient. This, in turn, will result in better proton range accuracy and, therefore, smaller planned tumor volumes (PTV). The hardware description and some reconstructed images have previously been reported. In a series of two contributions, we focus on presenting the software algorithms that convert pCT detector data to the final reconstructed pCT images for application in proton treatment planning. There were several options on how to accomplish this, and we will describe our solutions at each stage of the data processing chain. In the first paper of this series, we present the data acquisition with the pCT tracking and energy-range detectors and how the data are preprocessed, including the conversion to the well-formatted track information from tracking data and water-equivalent path length from the data of a calibrated multi-stage energy-range detector. These preprocessed data are then used for the initial image formation with an FDK cone-beam CT algorithm. The output of data acquisition, preprocessing, and FDK reconstruction is presented along with illustrative imaging results for two phantoms, including a pediatric head phantom. The second paper in this series will demonstrate the use of iterative solvers in conjunction with the superiorization methodology to further improve the images resulting from the upfront FDK image reconstruction and the implementation of these algorithms on a hybrid CPU/GPU computer cluster.

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