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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Laboratory tests of laser control of electron beams for future colliders

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser–beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

accelerator physics↗
DOE OSTI2025

Comparing optical four-flux model results with experimental data obtained by integrating sphere measurements

Four-flux theory is a way to model scattering through multiple layers of a system based on diffuse and collimated properties. When compared with measurement results obtained using an integrating sphere or a goniophotometer, an approximation is often made as the physical instrument cannot separate the collimated component from the diffuse light scattered in the forward direction. This paper tries to clarify the meaning of the word diffuse for the different cases and outlines simple corrections to improve the accuracy when comparing four-flux models and measured data based on sample haze and the geometry of the integrating sphere.

Bilokur, Maryna (ORCID:0000000191839650)↗
DOE OSTI2019

Adaptive control of laser-wakefield accelerators driven by mid-IR laser pulses

There has been growing interest both in studying high intensity ultrafast laser plasma interactions with adaptive control systems as well as using long wavelength driver beams. We demonstrate the coherent control of the dynamics of laser-wakefield acceleration driven by ultrashort (~ 100 fs) mid-infrared (~ 3.9 μ m) laser pulses. The critical density at this wavelength is 7.3 × 10 19 cm -3 , which is achievable with an ordinary gas target system. Interactions between mid-infrared laser pulses and such near-critical-density plasma may be beneficial due to much higher absorption of laser energy. In addition, the normalized vector potential of the laser field a 0 increases with longer laser wavelength, lowering the required peak laser intensity to drive non-linear laser-wakefield acceleration. Here, MeV level, collimated electron beams with non-thermal, peaked energy spectra are generated. Optimization of electron beam qualities are realized through adaptive control of the laser wavefront. A genetic algorithm controlling a deformable mirror improves the electron total charge, energy spectra, beam pointing and stability at various plasma density profiles. Particle-in-cell simulations reveal that the optimal wavefront causes an earlier injection on the density up-ramp and thus higher energy gain as well as less filamentation during the interaction, which leads to the improvement in electron beam collimation and energy spectra.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Automating Orbit Correction in the Main Injector 8 GeV Line

The Main Injector 8 GeV line (MI8 line) transports beam from Fermilab's Booster accelerator to either the Booster Neutrino experiments (BNB), the Recycler or the Main Injector. Often the orbit of the beam through the MI8 line differs depending on the beam destination. The beam is collimated in the MI8 line, so increasing intensities and repetition rates make controlling orbits through the collimators a necessity. The current method of regulating the MI8 line orbit with DC corrector settings is insufficient. A system named MITUNE is being developed to sample and categorize all beams through the MI8 line and automatically calculate and apply proper dipole corrector ramps to maintain desired orbits for pulses to any destination.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Synchronization and phase locking of resonant magnet power supplies for Mu2e experiment at Fermilab

The Mu2e Experiment has stringent beam structure requirements; namely, it requires short (~200 ns) proton bunches separated by 1.5-2.0 $\mu$s. This beam structure will be produced using the Fermilab 8 GeV Booster, the 8 GeV Recycler Ring, and the Delivery Ring, which was formerly part of the antiproton accumulator system. Out of time beam is limited to a fraction of level of no more than $1\times 10^{-10}$, a requirement known as "extinction". Achieving this level of extinction requires a system of resonant magnets and collimators, phased such that only in time particles will pass through. The Mu2e magnet system involves two components: a 300 kHz component, timed such that the 600 kHz beam will pass through the collimators at the nodes, and a 4.5 MHz system to reduce the slewing of the in-time beam. These two systems must be precisely phase locked to the bunch rate coming from the Delivery Ring, which itself must be phased to match beam transfers coming from the Recycler. This poster describes the control system for the magnets, which is based on an Intel Arria FPGA, which handles phase locking of the magnets to the Delivery Ring, including the phase jumps required to match transfers from the Recycler.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Design and Testing of Subsystems for Mo-99 Production

Argonne National Laboratory, in cooperation with Los Alamos National Laboratory, is developing technology with NorthStar Medical Technologies to produce 99 Mo from the γ,n reaction on a 100 Mo target in an electron accelerator. During production runs and thermal testing of the helium-cooled target, it became obvious that a production-scale beam-line configuration would need a collimator to protect the target from accidental beam misplacement or a beam-profile change. A prototype high-power collimator and beam stop were designed and fabricated. Testing indicated that they will be able to operate at full power in the production-scale accelerator.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Summary of Results for Idaho Accelerator Center (IAC) Experiments with Compact Electron Permanent Magnet Spectrometer (CEPMS)

The Compact Electron Permanent Magnet Spectrometer (CEPMS) shown in Figure 2 consists of collimation at the electron beam entrance, a vacuum chamber for beam transport and a removable 60 degree sector magnet constructed by SABR Enterprises (Ref 2) that is used to momentum analyze the incoming electron beam. There are electron detection planes located perpendicular to straight through and the 60 degree trajectory ports. The planes are designed to accept phosphor screens for time integrated measurements. The screens can be replaced by scintillator for time resolved measurements using gated or streak cameras. The length of the spectrometer along the beamline without the collimator is about 400mm (14”). The spectrometer requires no power supply with controls for cycling or cooling for the magnet. The entire assembly, with magnet installed, weighs about 35kg (75lbs) Figure 3 depicts central and extreme trajectories through the spectrometer for various electron energies. The chamber accommodates a +/-50mm wide detection field relative to the center trajectory. Trajectories with larger momentum (energy) are bent the least. Since the permanent magnet slides off and on with reference to the upstream edge of the vacuum chamber, it can be adjusted to various positions to slightly increase or decrease the central energy thereby changing the range of available energies. Figure 4 shows the effect of changing the location of the permanent magnet on the electron trajectory. A small inward change in r produces a longer trajectory in the magnet therefore, the same energy trajectory is bent more.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Imaging Electrons in Two Dimensional Materials (Final report)

Two-dimensional (2D) materials have extraordinary characteristics that offer promising new approaches for science and technology. Electrons in graphene can move ballistically through a sheet, even though it is only a single atom thick. And transition metal dichalcogenide materials can be cleaved into 2D flakes of all types – metals, semiconductors, insulators, magnetic materials, and superconductors. To benefit from these discoveries, the science needs to be understood to transform 2D materials into useful new devices and systems. The evolution in time of atomic scale graphene structures has been studied in time with a transmission electron microscope (TEM), and ballistic transport of electrons in graphene was been imaged using a cooled scanning probe microscope (SPM), as well as electron motion in MoS 2 . Graphene is only one atom thick but is extremely strong, creating the opportunity to fabricate atomic scale structures in the lateral direction. Using an atomic resolution TEM, a suspended sheet of graphene can be shaped by a Si impurity atom on its surface that acts like a chisel to open up apertures, one atom at a time. The electrons in the TEM provide both the chiseling energy and the ability to image the results. Electrons and holes in graphene form a new type of electronic system with conical conduction and valence bands that meet at the Dirac point, with no energy gap. For moderate densities, the carriers form a Fermi liquid with ballistic transport over micron-scale distances. Using a cooled SPM the cyclotron orbit of electrons in graphene has been imaged. In the magnetic focusing regime, electrons leaving a point contact circle around and leave from a second point contact when the cyclotron diameter is equal to the contact spacing. The paths of electrons are focused - they enter at different angles but converge again at the exiting contact. When the SPM tip knocks an electron out of its orbit, an imaging signal is created. The ballistic motion of carriers in graphene opens the way for ballistic devices that manipulate beams of electrons and holes. Our collaborator Gil-Ho Lee, in Philip Kim's group, created a collimating contact by placing zig-zag absorbers on either side of entering electrons. Our cooled SPM was used to image the electron beam and determine its 9-degree halfwidth. By changing the gate voltage, a collimated beam of holes was also created, opening the way for colliding beam experiments. Coherent beams of carriers are desirable for quantum information processing. Via Andreev reflection, superconducting contacts can covert Cooper pairs in a superconductor to an ingoing and outgoing electrons and holes. Using our cooled SPM, Andreev reflection was imaged from a superconducting contact on a graphene device. Magnetic focusing was used to create an incoming beam of electrons and an outgoing beam of holes, detected by a third point contact. The images show a clear transition from normal reflection above the superconducting transition temperature to Andreev reflection as the device is cooled. Transition metal dichalcogenides offer a wide array of materials that can be exfoliated into ultrathin 2D sheets. A cooled SPM can be used to detect quantum dots as well as to image electron flow. The tip charge capacitively couples to electrons on the dot, acting as a gate to tune the dot conductance. Coulomb blockade peaks appear as a bullseye pattern in an SPM image as the tip is raster scanned above the dot. This approach was used to detect quantum dots in a MoS 2 channel as the carrier density was reduced and electrons pooled in low energy points. Through our DOE supported research, cooled SPM imaging has proven to be a very useful tool to uncover the motion of electrons and holes in the new quantum materials graphene and MoS 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2021

Cross Section Measurements of Photonuclear Reaction Pathways Towards Promising Medical Radioisotopes

Project Objectives: The goal of this project was to generate data relevant to radioisotope production while developing innovative technologies that foster and enhance novel production of radioisotopes, and, also, while providing opportunities for cultivating and training future generations of scientists. This work has provided the foundation for methodologies for determination of photonuclear cross sections over multiple energies in a single irradiation. Simultaneously, the feasibility of electron LINAC production of several in-demand radioisotopes such as 47 Sc, 67 Cu, 77 As, and 186 Re has been demonstrated. To accomplish these objectives a collaboration was formed between two complimentary facilities, the Low Energy Accelerator Facility (LEAF) at Argonne National Laboratory and the High Intensity Gamma-ray Source (HIGS) at Triangular Universities Nuclear Laboratory (TUNL). The involvement of the research group from North Carolina Central University gave students at this Historically Black University experience in forefront nuclear-physics research relevant to addressing a high-priority interdisciplinary issue. Project Description: HIGS provides a nearly monoenergetic gamma-ray beam by intra-cavity Compton backscattering of free-electron photons from electrons circulating in a storage ring. This beam can be collimated to produce a very precise energy beam. If the beam is un-collimated a calculated and precise energy spread of the beam occurs radially. The γ-flux can be evenly distributed over the radial distribution of energy and used to perform activation experiments on concentric ring targets. Thus providing multiple energy ranges in a single irradiation. Each concentric ring target can be counted separately in order to determine activation at the given energy and successively be correlated to the activation cross section. Targets were activated to determine production feasibility using electron beams at LEAF. Potential Impact: The Nuclear Science Advisory Committee recently named production of radioisotopes with electron LINACs as one of the most compelling and largest-impact opportunities for the production of high specific activity radioisotopes. Improving the photonuclear cross sectional data base with experimentally verified results will greatly enhance a researcher’s ability to rationalize electron LINAC production routes towards desired radioisotopes. This work will provide the foundation for methodologies for determination of photonuclear cross sections over multiple energies and multiple targets in a single irradiation. The techniques developed in this project will enable future studies to continue verifying theoretically predicted photonuclear cross section with experimental results. These data will also enable adaptation of models and support more precise theoretical calculation of photonuclear cross sections. This research will involve undergraduates, graduate students, and post-docs to give them a valuable research experience leading towards the next generation of scientists in the field of medical isotopes.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2025

Accelerator Neutrinos

Neutrino beams from particle accelerators are vital for probing fundamental physics, enabling experiments like DUNE and NOvA to study neutrino oscillations and CP violation. These experiments push proton beam power to multi-MW levels and require precise beam instrumentation to manage flux and enhance precision. This talk will explore advancements in neutrino beam technology, highlighting the challenges and future prospects of high-intensity, well-collimated beams for next-generation accelerator facilities. Neutrino beams from particle accelerators are vital for probing fundamental physics, enabling experiments like DUNE and NOvA to study neutrino oscillations and CP violation. These experiments push proton beam power to multi-MW levels and require precise beam instrumentation to manage flux and enhance precision. This talk will explore advancements in neutrino beam technology, highlighting the challenges and future prospects of high-intensity, well-collimated beams for next-generation accelerator facilities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Gamma Spectrometry Code Rodeo for Uranium Enrichment—FY 2022 Report

In the first two quarters of FY22, data acquisition continued at ORNL and LLNL using uranium sources of known enrichments. This was an FY21 task which could not be completed in FY21 because of problems encountered with the ORNL M400 CZT in Q4 of FY21, and the subsequent repairs. The detector was received back from H3D in the first of September 2021 , and the measurements resumed . Measurements using the repaired detector were completed in Q1 of FY22. The spectra were distributed by ORNL to the analyzing labs. Analysis results were received in Q2 of FY2022. The results from the various codes were intercompared and an ANOVA analysis was performed. Random and systematic uncertainties were established for each code. The ANOVA results and discussions were included in a revised version of FY21Annual Report issued in March 2022. A paper was presented at the INMM 2022Annual Conference, with the analysis results from the various isotopic codes, and the ANOVA table with random and systematic uncertainties. The Project Work Plan (PWP) for FY22 included a task to perform field testing of the M400 CZT and the analysis codes using UF 6 cylinder measurements at the Framatome Fuel Fabrication Facility in Richland, WA. PNNL was the lead for the field testing task. PNNL drafted a Field Test Plan, and refined it based on comments received from the team. PNNL coordinated with Framatome facility, the logistics of carrying out the field testing . A collimator and shield made out of TFlex (tungsten impregnated polymer) was designed and professionally manufactured. The collimators were used in the field test measurements. The measurements at Framatome were completed on April 21, 2022. A total of 34 Type 30B cylinders were measured using three M400 detectors (PNNL, LLNL, and ORNL detectors). Measurements using M400 were taken at two locations on the side of each cylinder and from the end-on bottom location. Additionally, HPGe measurements were taken at the end-on location to establish ground truth. Cylinder wall thickness measurements were also made at all three locations. To gain a better understanding of the effect of background from surrounding cylinders, the same five cylinders measured individually in low background locations were measured again in the cylinder storage yards. Due to inclement weather, manufacturer delays, shipping delays, and equipment failure, the measurement campaign spanned twice as long compared to the original timeline. Gamma-ray spectra from M400 and HPGe detectors, along with the cylinder data and photographs were organized and shared with the collaborators for further analysis. Spectra were analyzed by the participating laboratories. FY22 PWP also consists of tasks related to plutonium source measurements, adapting the codes to analyze plutonium spectra, and inter-comparison of the results from various codes. Plutonium spectra are being acquired at LANL, ORNL, and LLNL. LANL, SNL and LLNL are in the process of modifying FRAM, GADRAS, and CZTU, respectively. The plutonium related tasks will be completed in Q2 of FY23.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

Automating Orbit Correction In The Main Injector 8 GeV Line

The Main Injector 8 GeV line (MI8 line) transports beam from Fermilab s Booster accelerator to either the Booster Neutrino experiments (BNB), the Recycler or the Main Injector. Often the orbit of the beam through the MI8 line differs depending on the beam destination. The beam is collimated in the MI8 line, so increasing intensities and repetition rates make controlling orbits through the collimators a necessity. The current method of regulating the MI8 line orbit with DC corrector settings is insufficient. A system named MITUNE is being developed to sample and categorize all beams through the MI8 line and automatically calculate and apply proper dipole corrector ramps to maintain desired orbits for pulses to any destination.

Hazelwood, K. J. [Fermilab]↗
DOE OSTI2020

The Role of Outflows, Radiation Pressure, and Magnetic Fields in Massive Star Formation

Stellar feedback in the form of radiation pressure and magnetically driven collimated outflows may limit the maximum mass that a star can achieve and affect the star formation efficiency of massive prestellar cores. Here we present a series of 3D adaptive mesh refinement radiation–magnetohydrodynamic simulations of the collapse of initially turbulent, massive prestellar cores. Our simulations include radiative feedback from both the direct stellar and dust-reprocessed radiation fields, and collimated outflow feedback from the accreting stars. We find that protostellar outflows punch holes in the dusty circumstellar gas along the star’s polar directions, thereby increasing the size of optically thin regions through which radiation can escape. Precession of the outflows as the star’s spin axis changes due to the turbulent accretion flow further broadens the outflow, and causes more material to be entrained. Additionally, the presence of magnetic fields in the entrained material leads to broader entrained outflows that escape the core. We compare the injected and entrained outflow properties and find that the entrained outflow mass is a factor of ∼3 larger than the injected mass and the momentum and energy contained in the entrained material are ∼25% and ∼5% of the injected momentum and energy, respectively. As a result, we find that, when one includes both outflows and radiation pressure, the former are a much more effective and important feedback mechanism, even for massive stars with significant radiative outputs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Structure of Exhausts in Magnetic Reconnection with an X-line of Finite Extent

We present quantitative predictions of the structure of reconnection exhausts in three-dimensional magnetic reconnection with an X-line of finite extent in the out-of-plane direction. Sasunov et al. showed that they have a tilted ribbon-like shape bounded by rotational discontinuities and tangential discontinuities. We show analytically and numerically that this prediction is largely correct. When there is an out-of-plane (guide) magnetic field, the presence of the upstream field that does not reconnect acts as a boundary condition in the normal direction, which forces the normal magnetic field to be zero outside the exhaust. This condition constrains the normal magnetic field inside the exhaust to be small. Thus, rather than the ribbon tilting in the inflow direction, the exhaust remains collimated in the normal direction and is forced to expand nearly completely in the out-of-plane direction. This exhaust structure is in stark contrast to the two-dimensional picture of reconnection, where reconnected flux expands in the normal direction. We present analytical predictions for the structure of the exhausts in terms of upstream conditions. The predictions are confirmed using three-dimensional resistive-magnetohydrodynamic simulations with a finite-length X-line achieved using a localized (anomalous) resistivity. Implications to reconnection in the solar wind are discussed. In particular, the results can be used to estimate a lower bound for the extent of the X-line in the out-of-plane direction solely using single-spacecraft data taken downstream in the exhausts.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Laboratory Tests of Laser Control of Electron Beams for Future Colliders

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser-beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

Accelerator Physics (physics.acc-ph)↗
NASA NTRS1972

Planetary X ray experiment

Design studies for an X-ray experiment using solid state detectors and for an experiment using a proportional counter for investigating Jovian and Saturnian magnetospheres are reported. Background counting rates through the forward aperture and leakage fluxes are discussed for each design. It is concluded that the best choice of instrument appears to have following the characteristics: (1) two separate multiwire proportional counters for redundancy; (2) passive collimation to restrict the field to about 5 deg, wiregrid modulation collimation to about 0.1 deg angular resolution; (3) no active shielding system around the counter body; and (4) light passive shielding around any portion of the counter body exposed to space to absorb most of the cosmic X-ray background.

Anderson, K. A.↗
NASA NTRS1972

Techniques in balloon X-ray astronomy.

Since the first balloon observation of the Crab Nebula balloon data have provided much information on the positions, spectra, time variability and pulsed nature of localized sources, and on the spectrum and isotropy of diffuse galactic and universal components. Measurements are limited to energies above about 20 keV by atmospheric attenuation at 2 to 3 g/sq cm depth and to below several hundred keV by detector sensitivity. Detectors usually consist of large-area Na I or Cs I scintillation counters with anticoincidence collimators for rejection of charged particles and scattered X-rays. Proportional counters are occasionally used at lower energies and solid-state detectors are used where extreme energy resolution is important. The instruments require a pointing capability on the order of 1.0 to 0.1 deg, depending on the collimator aperture. Digital data is either recorded on board or telemetered using a PCM technique.

Peterson, L. E.↗