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Smith, K.

Publications and source records attributed to Smith, K..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The EIC accelerator: design highlights and project status

The design of the electron-ion collider (EIC) at Brookhaven National Laboratory is well underway, aiming at a peak electron-proton luminosity of 10e+34 cm^-1·sec^-1. This high luminosity, the wide center-of-mass energy range from 29 to 141 GeV (e-p) and the high level of polarization require innovative solutions to maximize the performance of the machine, which makes the EIC one of the most challenging accelerator projects to date. The complexity of the EIC will be discussed, and the project status and plans will be presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Three-Dimensional Full-Core BEAVRS Using OpenMOC with Transport Equivalence

Using an optimized implementation of the three-dimensional (3D) method of characteristics for neutron transport, along with a novel equivalence method for transport calculations that was designed to correct self-shielding errors from neglecting the angular dependence of resonant group absorption, a 3D full-core light water reactor hybrid stochastic-deterministic eigenvalue calculation was achieved. This paper presents the optimizations developed and compares the transport solutions obtained. For the statepoint, run times near 10 000 CPU hours are achieved—improving on previous works by an order of magnitude—with near 1% error on pin fission to 238 U capture ratios and a few dozen pcms on the eigenvalue.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

High-power test results for a cylindrical-shell silicon carbide higher-order-mode damper

The next high-current Electron-Ion Collider (EIC) is a new accelerator to be built at Brookhaven National Laboratory in collaboration with Thomas Jefferson National Accelerator Facility. In the EIC Electron Storage Ring (ESR), there will be beam currents of up to 2.5 A, which will excite massive higher-order-mode (HOM) power in the 17 single-cell 591 MHz superconducting radio-frequency (SRF) cavities. Damping the HOM power in the ESR SRF cavities is a challenge. A room temperature cylindrical shell shape silicon carbide (SiC) beamline HOM absorber (BLA) was chosen as the baseline design, due to its broadband and high-power capability, and previous demonstrations at other accelerator facilities, albeit at much lower power. Because the EIC BLA HOM power dissipation is significantly greater than the previous applications, it is imperative to carry out high-power testing to determine the maximum device performance levels achievable for thermal transport, rf breakdown, and mechanical stress, prior to finalizing the design. A SiC HOM absorber with a state-of-the-art geometry size was prototyped to verify the shrink-fit technique, test outgassing rate, and high-power handling capability. This paper presents the HOM damper’s prototyping and test results. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

High Power Test Results For A Cylindrical-Shell SiC Higher-Order-Mode DAMPER

The next high-current Electron Ion Collider (EIC) is a new accelerator to be built at Brookhaven National Laboratory (BNL) in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). In the EIC Electron Storage Ring (ESR), there will be beam currents up to 2.5 A, which will excite massive Higher-Order-Modes (HOM) power in the 17 single-cell 591 MHz Superconducting Radio Frequency (SRF) cavities. To damp the HOM power in the ESR SRF cavities is a challenge. A room temperature cylindrical shell shape Silicon Carbide (SiC) Beamline HOM Absorber (BLA) was chosen as the baseline design, due to its broadband and high-power capability, and previous demonstrations at other accelerator facilities, albeit at much lower power. Because the EIC BLA HOM power dissipation is significantly greater than the previous applications, it is imperative to carry out high power testing to determine the maximum device performance levels achievable for thermal transport, RF breakdown, and mechanical stress, prior to finalizing the design. A SiC HOM absorber with state-of-the-art geometry size was prototyped to verify shrink-fit technique, test outgassing rate, and high power handling capability. This paper presents the HOM damper’s prototyping and test results.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Measurement of the 13 C(α, n 0 ) 16 O Differential Cross Section from 0.8 to 6.5 MeV

The cross section of the 13 C(α, n 0 ) 16 O reaction is needed for nuclear astrophysics and applications to a precision of 10% or better, yet inconsistencies among 50 years of experimental studies currently lead to an uncertainty of ≈15%. Here, using a state-of-the-art neutron detection array, we have performed a high resolution differential cross section study covering a broad energy range. These measurements result in a dramatic improvement in the extrapolation of the cross section to stellar energies potentially reducing the uncertainty to ≈5% and resolving long standing discrepancies in higher energy data.

6 ≤ A ≤ 19↗
DOE OSTI2023

Designing a boron nitride polyethylene composite for shielding neutrons

Neutrons are encountered in many different fields, including condensed matter physics, space exploration, nuclear power, and healthcare. Neutrons interacting with a biological target produce secondary charged particles that are damaging to human health. The most effective way to shield neutrons is to slow them to thermal energies and then capture the thermalized neutrons. These factors lead us to consider potential materials solutions for neutron shields that maximize the protection of humans while minimizing the shield mass and adapt well to modern additive manufacturing techniques. Using hexagonal boron nitride (hBN) as a capture medium and high-density polyethylene (HDPE) as a thermalization medium, we aim to design the optimal internal structure of h 10 BN/HDPE composites by minimizing the effective dose, which is a measure of the estimated radiation damage exposure for a human. Through Monte Carlo simulations in Geant4, we find that the optimal structure reduces the effective dose up to a factor of 72 over aluminum (Al) and up to a factor of 4 over HDPE; this is a significant improvement in shielding effectiveness that could dramatically reduce the radiation exposure of occupational workers.

36 MATERIALS SCIENCE↗
DOE OSTI2023

First Direct Measurement Constraining the Ar 34 ( α , p ) K 37 Reaction Cross Section for Mixed Hydrogen and Helium Burning in Accreting Neutron Stars

The rate of the final step in the astrophysical αp process, the 34 Ar(α,p) 37 K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. Here, we present the first direct measurement constraining the 34Ar(α,p)37K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the 34 Ar,Cl(α,p) 37 K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The 34 Ar(α,2p) 36 Ar cross section, which can be exclusively attributed to the 34 Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

The mapping & avoidance of high order cavity modes

In this paper a technique developed in 2016 is presented for mapping the multidimensional, multi-mode high order mode landscape of a beam driven super conducting RF cavity. The initial use case for this technique was intended to allow longitudinal gradient control of a beam driven super conducting cavity while simultaneously avoiding many dangerous high order modes and excessive component stresses. This paper will focus on the stability and component stress considerations of the 56MHz superconducting cavity, located in the 4 o’clock sector interaction region of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The 56MHz cavity is intended to work in conjunction with the Stochastic Cooling system to improve the longitudinal confinement in the central 197MHz RF bucket and thus increase the integrated luminosity during heavy ion beam runs at RHIC.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

M4SF-22LL010302052-Radionuclide Incorporation Model for Corrosion Products

This progress report (Level 4 Milestone Number M4SF-22LL010302052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Crystalline Activity Number SF-22LL01030205. The research is focused on actinide and radionuclide sequestration in steel corrosion products.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Design of the Electron Ion Collider Electron Storage Ring SRF cavity

The Electron Ion Collider (EIC) under construction at Brookhaven National Laboratory is a high luminosity collider as the next major research facility for the nuclear physics community. Among the numerous RF subsystems in the EIC, the electron storage ring (ESR) fundamental RF cavities system is one of the most challenging. This system will handle a high beam current of up to 2.5A and replenish up to 10MW of beam power losses from synchrotron radiation and HOM. Variable coupling is required in the cavities due to the wide range of required total RF voltage and beam current combinations. In this paper, we will present the status of the design and future plans.

Guo, J.↗
DOE OSTI2022

Correction of crosstalk effect in the Low Energy RHIC electron Cooler Booster Cavity

we report that the Low Energy Relativistic Heavy Ion Collider (RHIC) electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with rms dp/p less than 5e-4. The superconducting radiofrequency (SRF) Booster Cavity is the major accelerating component in LEReC. It is a 0.4 cell cavity operating at 2 K, providing a maximum energy gain of 2.2 MeV. It is modified from an experimental Energy Recovery Linac (ERL) photocathode gun, and thus has fundamental power couplers (FPCs), pickup (PU) couplers (field probes) and HOM coupler close to each other on the same side of the cavity. Direct capacitive coupling between the FPC and PU, called the crosstalk effect, combined with microphonic detuning, can induce closed loop voltage fluctuations that exceed the total energy spread requirement of LEReC. The crosstalk effect in this cavity is modelled, simulated, and measured, and a correction method is proposed and demonstrated to suppress the voltage fluctuation so that energy spread requirement can be met.

43 PARTICLE ACCELERATORS↗