At Lawrence Berkeley National Laboratory, the ALS-U project will enable transformative science that cannot be performed on any existing or planned light source in the world by upgrading the Advanced Light Source (ALS). The ALS is a synchrotron dedicated to generate bright beams of x-ray light and make it available to scientists from all over the world to fill their experimental needs, and where they can choose among 40 experiments or beamlines to perform their measurements. Some of the research that the ALS helps scientists with include material science, biology, chemistry, physics, and the environmental sciences.

The generated beams at the ALS must be filtered to select the wavelength needed for the experiments and adaptive x-ray optics (AXO) and grating monochromators are two key components of the beam system in the ALS-U that enable coherence. The use of AXO and grating monochromators has not been fully explored, through simulations it can be shown that AXO and monochromators can compensate for the line position errors in the wavefront to achieve coherence, and that it works for multiple colors and, variable-line-spacing gratings. 

In particle physics, jets are showers of particles made of quarks. Semi visible jets (SVJ) include dark jets (dark quarks) that interact with the detector and those that don’t, this results in missing energy in the measurements. There are two mediators which are thought to give rise to semi-visible jets: t-channel (with particle Phi as a mediator) and s-channel (with particle Z’ as a mediator). Semi-visible jets are part of the dark sector searches that have not been explored yet, therefore it is important to create a good model to reconstruct semi-visible jets to be able to differentiate them from other jets in experiments. 

There is an important parameter to take into account in the model for semi-visible jets and that is the parameter "r_inv"  which allows semi-visible jets, i.e., it establishes how visible a jet is. "R_inv"  ranges from fully invisible ("r_inv"   = 0) to fully visible ("r_inv"   = 1). 

To reconstruct  semi-visible jets,  known jets (also called truth) can be "matched" with reconstructed jets to understand how different cone sizes jets capture information of semi-visible jets. By finding the number of reconstructed jets that are within the cone size of truth jets, this is what we call ‘matching jets’. Then we can compare those matched jets to those found in QCD and see if we find this number of jets.

In the interior of a nucleus we encounter neutrons and protons, collectively referred to as nucleons which constitute what is defined as nuclear matter. There are interesting properties of nuclear matter to study such as the energy per nucleon, saturation density, saturation energy density, incompressiblity, and symmetric energy. 

A key part to study these properties is having a good potential model for two interacting nucleons. The Hamada-Johnston (HJ) potential model is a good model that describes the scattering data and with deuteron properties. The potential includes four parts: the central part, the spin-orbit part, the quadratic spin-orbit part, and the tensor part. 

The azimuthal quantum number L, the additional azimuthal quantum number L_0 for the deuteron state, the spin quantum number S, the total angular momentum J, and the isospin quantum number T, are used to write the spectroscopic notation for the potentials for different nucleon-nucleon states as follows: V ( 2S+1LJ ) for L = L_0 , with the exception of the deuteron superposition states: V ( 2S+1LJ +2S+1 LJ )_{LL_0}; with the rule that the summation of the quantum numbers L+S +T or L_0 + S + T is always odd for any state obeying the Pauli principle. 

Although famous for being toxic, arsenic (As) can be used as tracer to produce internal images of the body to locate cancers or metastasis. This method is called positron emission tomography (PET) imaging, where a patient receives a dose of an isotope such as arsenic to create the images, at the same time, this same dose can be used for tumor elimination. 

The decay properties of the isotopes used need to be fully identified prior to determination of the dose needed for treatments. The National Nuclear Data Center at Brookhaven National Laboratory analyses gamma-ray spectra to provide the mentioned properties by studying the decay scheme of isotopes.

Germanium detectors record the gamma-rays emitted from the decay of Arsenic-71 to Germanium-71 as electrical pulses. From these recordings, a spectrum is formed where we need to take into account the presence of other gamma-rays belonging to other arsenic isotopes  and energies due to other physical processes (such as x-rays). 

The decay scheme is then made and looks like the image on the left. The decay scheme was revised based on gamma-gamma coincidence technique, in which a short time interval is imposed for the measurement of the gamma-ray energies. By measuring centroid peaks the energies were measured and, by measuring the areas of the peaks the relative intensities were calculated. The results show the addition of transition energy 185.6 keV, as well as the elimination of 39 transitions and levels in the decay scheme of 71As.