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Abstract not provided.

In the first meiotic cell division, proper segregation of chromosomes in most organisms depends on chiasmata, exchanges of continuity between homologous chromosomes that originate from the repair of programmed double-strand breaks (DSBs) catalyzed by the Spo11 endonuclease. Since DSBs can lead to irreparable damage in germ cells, while chromosomes lacking DSBs also lack chiasmata, the number of DSBs must be carefully regulated to be neither too high nor too low. Here, we show that inCaenorhabditis elegans, meiotic DSB levels are controlled by the phosphoregulation of DSB-1, a homolog of the yeast Spo11 cofactor Rec114, by the opposing activities of PP4^PPH-4.1phosphatase and ATR^ATL-1kinase. Increased DSB-1 phosphorylation inpph-4.1mutants correlates with reduction in DSB formation, while prevention of DSB-1 phosphorylation drastically increases the number of meiotic DSBs both inpph-4.1mutants and in the wild-type background.C. elegansand its close relatives also possess a diverged paralog of DSB-1, called DSB-2, and loss ofdsb-2is known to reduce DSB formation in oocytes with increasing age. We show that the proportion of the phosphorylated, and thus inactivated, form of DSB-1 increases with age and upon loss of DSB-2, while non-phosphorylatable DSB-1 rescues the age-dependent decrease in DSBs indsb-2mutants. These results suggest that DSB-2 evolved in part to compensate for the inactivation of DSB-1 through phosphorylation, to maintain levels of DSBs in older animals. Our work shows that PP4^PPH-4.1, ATR^ATL-1, and DSB-2 act in concert with DSB-1 to promote optimal DSB levels throughout the reproductive lifespan.

Fast and heavy inorganic scintillators with suitable radiation tolerance are required to face the challenges presented at future hadron colliders of high energy and intensity. Up to 5 GGy and 5 × 10¹⁸ n_eq/cm² of one-MeV-equivalent neutron fluence is expected by the forward calorimeter at the Future Hadron Circular Collider. This paper reports the results of an investigation of proton- and neutron-induced radiation damage in various fast and heavy inorganic scintillators, such as LYSO:Ce crystals, LuAG:Ce ceramics, and BaF₂ crystals. The experiments were carried out at the Blue Room with 800 MeV proton fluence up to 3.0 × 10¹⁵ p/cm² and at the East Port with one MeV equivalent neutron fluence up to 9.2 × 10¹⁵ n_eq/cm², respectively, at the Los Alamos Neutron Science Center. Experiments were also carried out at the CERN PS-IRRAD proton facility with 24 GeV proton fluence up to 8.2 × 10¹⁵ p/cm². Research and development will continue to develop LuAG:Ce ceramics and BaF₂:Y crystals with improved optical quality, F/T ratio, and radiation hardness.

Here, we report measurements of forward jets produced in Cu + Au collisions at $$\sqrt{s{NN}}$$=200 GeV at the Relativistic Heavy Ion Collider. The jet-energy distributions extend to energies much larger than expected by Feynman scaling. This constitutes the first clear evidence for Feynman-scaling violations in heavy-ion collisions. Such high-energy particle production has been in models via QCD string interactions, but so far is untested by experiment. One such model calls this a hadronic accelerator. Studies with a particular heavy-ion event generator (HIJING) show that photons and mesons exhibit such very high-energy production in a heavy-ion collision, so a QCD accelerator appropriately captures the physics associated with such QCD string interactions. All models other than HIJING used for hadronic interactions in the study of extensive air showers from cosmic rays either do not include these QCD string interactions or have smaller effects from the QCD accelerator.

The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. Here, in this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required for the future of ECCE are described.

The proposed high-luminosity high-energy Electron-Ion Collider (EIC) will provide a clean environment to precisely study several fundamental questions in the fields of high-energy and nuclear physics . A low material budget and high granularity silicon vertex/tracking detector is critical to carry out a series of hadron and jet measurements at the future EIC especially for the heavy flavor product reconstruction or tagging. The conceptual design of a proposed forward silicon tracking detector with the pseudorapidity coverage from 1.2 to 3.5 has been developed in integration with different magnet options and the other EIC detector sub-systems. The tracking performance of this detector enables precise heavy flavor hadron and jet measurements in the hadron beam going direction. The detector R&D for the proposed silicon technology candidates: Low Gain Avalanche Diode (LGAD) and radiation hard depleted Monolithic Active Pixel Sensor (MALTA), which can provide good spatial and timing resolutions, is underway. Bench test results of the LGAD and MALTA prototype sensors will be discussed.

The LANL EIC team would like to contribute to the EIC silicon vertex/tracking detector design, construction, commissioning and operation. Our primary focus is for a proposed forward silicon tracker with pseudorapidity coverage from 1 to 3.5 in the nucleon/nuclei beam going (forward) direction at IP-6 of the EIC. LANL LDRD is currently supporting this effort from FY20-FY22 with a funding of $5M. Meanwhile, we are open to collaborate on the other EIC detector sub-systems such as the central, backward silicon vertex/tracking detectors and/or a precision timing detector based on the LGAD technology.

The first year review of the project is presented, including the following topics: introduction of the EIC; project team and resources; project scope, science and outreach; feasibility review; minimal and stretch goals; organization chart - theory; summary of project deliverables met; detailed account of perturbative QCD accomplishments; and conclusions.