Beam Energy Research Articles

Core excitation in 92Mo up to high-spin

Abstract An in-beam gamma-ray spectroscopy study of the even-even nucleus 92Mo
has been carried out using the 30Si + 65Cu, 18O + 80Se reactions at beam energies of
120 and 99 MeV, respectively. Angular distribution from oriented state ratio (RADO)
and linear polarization (Δasym) measurements have fixed most of the tentatively
assigned spin-parity of the high energy levels. A large-scale shell-model calculation
using the GWBXG interaction has been carried out to understand the configuration
and structure of both positive and negative parity states up to the highest observed
spin. The high-spin states primarily originate from the coupling of excited proton and
neutron-core structures in an almost stretched manner. The systematics of energy
required for forming a neutron particle-hole pair excitation, νg9/2→νd5/2, is discussed.
Lifetime of few high-spin states have been measured using DSAM. Additionally, a
qualitative argument is proposed to explain the comparatively strong E1 transition
feeding the 7310.9-keV level.

Spatially Fractionated Radiotherapy with Very High Energy Electron Pencil Beam Scanning.


To evaluate spatially fractionated radiation therapy (SFRT) for very-high-energy electrons (VHEEs) delivered with pencil beam scanning. Radiochromic film was irradiated at the CERN Linear Electron Accelerator for Research (CLEAR) using 194 MeV electrons with a step-and-shoot technique, moving films within a water tank. Peak-to-valley dose ratios (PVDRs), depths of convergence (PVDR≤1.1), peak doses, and valley doses assessed SFRT dose distribution quality. A Monte Carlo (MI) model of the pencil beams was developed using TOPAS and applied to a five-beam VHEE SFRT treatment for a canine glioma patient, compared to a clinical 6 MV VMAT plan. The plans were evaluated based on dose-volume histograms, mean dose, and maximum dose to the planning target volume (PTV) and organs at risk (OARs).
Main Results:
Experimental PVDR values were maximized at 15.5 ± 0.1 at 12 mm depth for 5 mm spot spacing. A depth of convergence of 76.5 mm, 70.7 mm, and 56.6 mm was found for 5 mm, 4 mm, and 3 mm beamlet spacings, respectively. MC simulations and experiments showed good agreement, with maximum relative dose differences of 2% in percentage depth dose curves and less than 3% in beam profiles. Simulated PVDR values reached 180 ± 4, potentially achievable with reduced leakage dose. VHEE SFRT plans for the canine glioma patient showed a decrease in mean dose (>16%) to OARs while increasing the PTV mean dose by up to 15%. Lowering beam energy enhanced PTV dose homogeneity and reduced OAR maximum doses. The presented work demonstrates that pencil beam scanning SFRT with VHEEs could treat deep-seated tumors such as head and neck cancer or lung lesions, though small beam size and leakage dose may limit the achievable PVDR.&#xD.

Proton bunch monitors for the clinical translation of prompt gamma-ray timing

Objective. Prompt gamma-ray timing is an emerging technology in the field of particle therapy treatment verification. This system measures the arrival times of gamma rays produced in the patient body and uses the cyclotron radio frequency signal as time reference for the beam micro-bunches. Its translation into clinical practice is currently hindered by observed instabilities in the phase relation between the cyclotron radio frequency and the measured arrival time of prompt gamma rays. To counteract this, two proton bunch monitors are presented, integrated into the prompt gamma-ray timing workflow and evaluated.Approach. The two monitors are (a) a diamond detector placed at the beam energy degrader, and (b) a cyclotron monitor signal measuring the phase difference between dee current and voltage. First, the two proton bunch monitors as well as their mutual correlation were characterized. Then, a prompt gamma-ray timing measurement was performed aiming to quantify the present magnitude of the phase instabilities and to evaluate the ability of the proton bunch monitors to correct for these instabilities.Main results. It was found that the two new monitors showed a very high correlation for intermediate proton energies after the first second of irradiation, and that they were able to reduce fluctuations in the detected phase of prompt gamma rays. Furthermore, the amplitude of the phase instabilities had intrinsically decreased from about 700 ps to below 100 ps due to cyclotron upgrades.Significance. The uncertainty of the prompt gamma-ray timing method for proton treatment verification was reduced. For routine clinical application, challenges remain in accounting for detector load effects, temperature drifts and throughput limitations.

Joint Design of Altitude and Channel Statistics Based Energy Beamforming for UAV-Enabled Wireless Energy Transfer

In recent years, UAV-enabled wireless energy transfer (WET) has attracted significant attention for its ability to provide ground devices with efficient and stable power by flexibly navigating three-dimensional (3D) space and utilizing favorable line-of-sight (LoS) channels. At the same time, energy beamforming utilizing multiple antennas, in which energy beams are focused toward devices in desirable directions, has been highlighted as a key technology for substantially enhancing radio frequency (RF)-based WET efficiency. Despite its significant utility, energy beamforming has not been studied in the context of UAV-enabled WET system design. In this paper, we propose the joint design of UAV altitude and channel statistics based energy beamforming to minimize the overall charging time required for all energy-harvesting devices (EHDs) to meet their energy demands while reducing the additional resources and costs associated with channel estimation. Unlike previous works, in which only the LoS dominant channel without small-scale fading was considered, we adopt a more general air-to-ground (A2G) Rician fading channel, where the LoS probability as well as the Rician factor is dependent on the UAV altitude. To tackle this highly nonconvex and nonlinear design problem, we first examine the scenario of a single EHD, drawing insights by deriving an optimal energy beamforming solution in closed form. We then devise efficient methods for jointly designing altitude and energy beamforming in scenarios with multiple EHDs. Our numerical results demonstrate that the proposed joint design considerably reduces the overall charging time while significantly lowering the computational complexity compared to conventional methods.

RADT-31. EMBRACING HYPOFRACTIONATED RADIOTHERAPY FOR GLIOBLASTOMA IN A RESOURCE CONSTRAINED SETTING

Abstract BACKGROUND Various hypofractionated schedules of radiation have been tried in glioblastoma with limited success. Though the shorter fractionation is appealing and there is evidence (since 2017) to use the 40Gy in 15 fractions regime in the elderly, the fear of toxicity limits its use, especially in the developing nations. We have tried this regime in younger patients (not eligible for supportive care alone) who had a poor Performance status or if only a biopsy had been performed. METHODS 25 patients treated for glioblastoma from 2017 to 2023 using 4000cGy delivered in 15 fractions were included in the study. The patient details were obtained retrospectively from the medical records and the Eclipse Treatment Planning system. RESULTS There were 16 males and 9 females. Median age was 62 years (range 52 to 77 years). 56% of the patients had an ECOG performance score of 3; and the rest 2. 12 lesions were on the Right side, 9 in the left and the rest extended across the midline. Surgery was limited to biopsy alone in 8; almost as many (n=7) had a Near Total Resection; the rest underwent decompression. Surprisingly, almost half the patients were MGMT unmethylated. 16 patients were on steroids either during or after radiation. All 25 maintained their Performance Status and completed radiation as planned. The mean GTV Volume - 53.48 cc (Range 6-201). Dmax was never above 103%; Brainstem and Optic Apparatus Dmax were also kept below 100%. In the majority, 3 beams of mixed energy were used. 19 patients received both Concurrent and adjuvant temozolomide; only adjuvant was given to 6. The median overall survival was 7.7 months (range 2-60.6 months) and the Disease free survival was 7.5 months (Range 1-60.5 months). CONCLUSIONS Hypofractionated radiotherapy of 4000 cGy in 15 fractions seems to be a kinder treatment in glioblastoma patients with a poor performance status.

Simulation Study of High-Precision Characterization of MeV Electron Interactions for Advanced Nano-Imaging of Thick Biological Samples and Microchips

The resolution of a mega-electron-volt scanning transmission electron microscope (MeV-STEM) is primarily governed by the properties of the incident electron beam and angular broadening effects that occur within thick biological samples and microchips. A precise understanding and mitigation of these constraints require detailed knowledge of beam emittance, aberrations in the STEM column optics, and energy-dependent elastic and inelastic critical angles of the materials being examined. This simulation study proposes a standardized experimental framework for comprehensively assessing beam intensity, divergence, and size at the sample exit. This framework aims to characterize electron-sample interactions, reconcile discrepancies among analytical models, and validate Monte Carlo (MC) simulations for enhanced predictive accuracy. Our numerical findings demonstrate that precise measurements of these parameters, especially angular broadening, are not only feasible but also essential for optimizing imaging resolution in thick biological samples and microchips. By utilizing an electron source with minimal emittance and tailored beam characteristics, along with amorphous ice and silicon samples as biological proxies and microchip materials, this research seeks to optimize electron beam energy by focusing on parameters to improve the resolution in MeV-STEM/TEM. This optimization is particularly crucial for in situ imaging of thick biological samples and for examining microchip defects with nanometer resolutions. Our ultimate goal is to develop a comprehensive mapping of the minimum electron energy required to achieve a nanoscale resolution, taking into account variations in sample thickness, composition, and imaging mode.

Optimizing Power Density in Partially Coated Cantilever Beam Energy Harvesters: A Cost-Effective Design Strategy

Optimizing Power Density in Partially Coated Cantilever Beam Energy Harvesters: A Cost-Effective Design Strategy

Reduction of arrival time jitter or energy spread with arclike variable bunch compressors

Synchronizing free-electron laser pulses for time-resolved experiments is necessary as an unsynchronized system reduces the effective repetition rate of the experiment. Additionally, free-electron laser longitudinal coherence and spectral brightness are limited by electron beam energy spread. In this paper, a variable bunch compressor design and compression schemes were developed to: reduce klystron-induced arrival time jitter by 85% while preserving peak current and transverse emittance and to minimize electron beam correlated energy spread for potential self-seeding or HB-SASE modes. Published by the American Physical Society 2024

Development and commissioning of ion-optical elements for ion and antiproton beams with energies up to 5 keV

In nuclear and atomic physics experiments, charged ion beams often need to be guided from the ion production to the experimental site. In the PUMA experiment, an ion source beamline was developed, which can be operated with up to 5 keV beam energy at a base pressure of 10-9 mbar or better. In this technical report, a low-energy pulsed drift tube for beam energy modification, a hybrid einzel lens assembly for beam focusing and steering and an iris shutter assembly for separating beamline sections with different vacuum requirements are described with their design principles and performances.

The design of high-brightness ERL-FEL injector based on VHF electron gun

In the past decade, the fourth-generation light source based on the combination of Energy Recovery Linac (ERL) and Free-Electron Laser (FEL) using superconducting linear accelerators has garnered significant attention. It holds immense potential, particularly in generating high-power Extreme Ultraviolet (EUV) light sources. This article primarily focuses on the physical design of an injector for ERL-FEL, based on a Very High Frequency (VHF) electron gun with a charge of 100 pC. The beam energy is accelerated to 10 MeV using 3-cell superconducting cryomodule. The optimization of beam parameters is conducted through employment of BMad and ASTRA simulations, incorporating the concept of Merger optimization. The beam emittance is less than 0.6 mm mrad, and the peak current at the injector exit exceeds 18 A. We present a new method to evaluate the Longitudinal Space Charge (LSC) effects in merger sections, which can be readily applied in design work. Furthermore, we introduce a novel type of merger. The performance of this new merger is comparable to the previously known optimum, the zigzag merger, offering a potential alternative solution for injectors in ERLs.

High-count-rate particle tracking in proton and carbon radiotherapy with Timepix2 operated in ultra-short acquisition time

This work investigates the operational acquisition time limits of Timepix3 and Timepix2 detectors operated in frame mode for high-count rate of high deposited energy transfer particles. Measurements were performed using alpha particles from a 241Am laboratory source and proton and carbon ion beams from a synchrotron accelerator. The particle count rate upper limit is determined by overlapping per-pixel particle signals, identifiable by the hits per pixel counter > 2, indicating the need to decrease acquisition time. On the other hand, the lower limit is the time required to collect the particle deposited charge while maintaining spectral properties. Different acquisition times were evaluated for an AdvaPIX Timepix3 detector (500 μm Silicon sensor) with standard per-pixelDigital to Analog Converter (DAC)settings and a Minipix Timepix2 detector (300 μm Silicon sensor) with standard and customized settings the pulse shaping parameter and threshold. For AdvaPIX Timepix3, spectra remained accurate down to 100 μs frame acquisition time; at 10 μs, loss of collected charge occurred, suggesting either avoiding this acquisition time or applying a correction. Timepix2 allowed acquisition times down to 100 ns for single particle track measurements even for high energy loss, enabled by a new Timepix2 feature delaying shutter closure until full particle charge collection. This work represents the first measurement utilizing Timepix-chips pixel detectors in an accelerator beam of clinical energy and intensity without the need to decrease the beam current. This is made possible by exploiting the short shutter feature in Timepix2 and a customized per-pixel energy calibration of the Timepix2 detector with a larger discharging signal value which allowed for shorterTime-over-Threshold (ToT)signal. These customized settings extend the operation of the pixel detectors to higher event rates up to 109 particles/cm2/s.

Characterization of Cherenkov detectors for the MOLLER experiment

The MOLLER (Measurement Of Lepton Lepton Electroweak Reaction) experiment is aiming to measure the parity-violating asymmetry (Apv) in electron–electron (Møller) scattering with unprecedented precision. The flux of Møller scattered electrons from the liquid hydrogen target is measured using Cherenkov detectors and the longitudinal polarization of the incoming electron beam is rapidly flipped to extract the right-left fractional flux difference and thence Apv. The Cherenkov detector prototypes were tested at the MAMI accelerator facility in Mainz, Germany with an electron beam of energy ∼ 855 MeV.A brief overview of the experimental goals, design and performance of the prototype detectors with the electron beam are presented in this article.

Measurement of the 116Sn(18O, 18Ne)116Cd double charge exchange reaction at 276 MeV

The measurement of the 116Sn(18O, 18Ne)116Cd double charge exchange reaction cross section at very forward angles was performed for the first time at INFN-LNS using the MAGNEX magnetic spectrometer. This study, carried out at 276 MeV beam energy, provides a cross section of 34 nb ([9, 44] nb at 95% confidence level), confirming the tiny values recently obtained for the same reaction in other nuclides. This result has a major impact on the forthcoming systematic investigation of 0νββ decay candidates carried out by the NUMEN project, since it allows to properly tailor future experiments with high-intensity beams. The ultimate goal of this exploration is to experimentally access information about nuclear matrix elements relevant to the 0νββ decay rate.

Production of 43Sc and 44gSc from natural CaF2 material using an FN Tandem Accelerator

The radioisotopes of 43Sc and 44Sc are promising in the field of theranostics for their role as β+ emitters in theranostic pairs with 47Sc. Production of these isotopes through various nuclear reactions using either cyclotrons or linear accelerators is of particular interest and previous studies have provided results using accelerated beams of protons, deuterons, and alpha particles. A novel production technique, using an ion source cathode packed with natural calcium fluoride material and irradiated with a 3He beam, was tested at the Nuclear Science Laboratory at the University of Notre Dame in order to initially study the production of 41Ca. Gamma-ray spectrometry revealed presence of 43Sc and 44Sc in the target, and allowed for the first measurement of their yield due to reactions of 3He on natural calcium. The calculated thick target yields of 43Sc and 44gSc from the reactions natCa(3He,x)43Sc and natCa(3He,x)44gSc are compared to theoretical results using TALYS cross section models. Overall, results agree well with models at lower beam energies but tend to diverge at higher energies.

160 kW beam commissioning for the Rapid Cycling Synchrotron of the China Spallation Neutron Source

For the China Spallation Neutron Source (CSNS), the rapid cycling synchrotron (RCS)accumulates and accelerates the injection beam to the design energy of 1.6 GeV and then extractsthe high energy beam to the target. In this paper, the 160 kW beam power commissioning forthe CSNS RCS has been comprehensively studied, including: increase in the pulse width ofthe injection beam to optimize the transverse painting, commissioning of the two dualharmonic radio frequency (RF) cavities, optimization of the transverse and momentum collimators,longitudinal dynamic optimization, beam instability suppression,global closed orbit correction, local closed orbit correction, optimization of the RCS occasionallarge beam loss, optimization of the extraction mode and extraction occasional large beam loss,and so on.In order to meet the requirements of beam power increase and stable operation of the accelerator,the RCS beam losses from different sources are studied and optimized. With the aid of weeklyradiation dose measurement, the hot spots of the RCS are studied in depth to explore the causes.

Lebt of the Heavy Ion Linear Accelerator

At the NRC “Kurchatov Institute” (Kurchatov Complex for Theoretical and Experimental Physics), the pulsed linear resonant heavy ion accelerator is being developed. The Low Energy Beam Transport (LEBT) channel transports the beam from a laser-plasma source of multi-charged ions with an A/Z ratio from 4 to 8 (up to Bi27+) to the RFQ. This paper shares the results of the beam dynamics simulation of the LEBT, which ensures the separation of the working fraction of the ion beam and its matching with the RFQ.

Collision energy dependence of elliptic flow of identified hadrons in heavy-ion collisions using the PHSD model

We report the first predictions of elliptic flow (v2) of identified hadrons at mid-rapidity (|y|< 1.0) in Au+Au collisions at Elab=6.7,8,11,and 25 A GeV using the Parton Hadron String Dynamics (PHSD) model. The transverse momentum (pT) dependence of identified hadron v2 in different centrality intervals (0-10%, 10-40%, and 40-80%) is shown. A clear centrality dependence of v2(pT) is observed for particles at Elab=6.7,8,11,and 25 A GeV. Within the PHSD model, the number of constituent quark (NCQ) scaling of v2 approximately follows in Au+Au collisions at all beam energies. A collision energy (sNN) dependence of π, K, and pv2 is studied in comparison with available published experimental data in the beam energy range of 6-25 A GeV. These predictions will help in interpreting the data from the forthcoming Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) and Multi-Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA).

Recent progress and future plan for STCF collider ring lattice design

The Super Tau-Charm Facility (STCF) is a proposed dual-ring electron–positron collider in China, designed to operate at a center-of-mass energy (CME) range of 2–7[Formula: see text]GeV with symmetric beam energies. The collider aims for a luminosity exceeding [Formula: see text] at the beam energy of 2.0[Formula: see text]GeV. This work presents the preliminary lattice design for the STCF collider ring, specifically optimized for the 2.0[Formula: see text]GeV beam energy. To improve the nonlinear dynamics performance, the optimization of lattice is carried out by adjusting the strengths of sextupole and octupole magnets following the tuning of phase advances.

Focused Ion Beam Milling as a Method for Machining Explosive Crystals**

AbstractExperimental pore collapse studies have traditionally relied on machining methods that are mechanically active and result in rough surfaces, added stresses, and premature material fractures which are a source of experimental error. This work focuses on the method development and the results of adapting the focused ion beam to mill micro and nano‐scale pores with increased geometrical freedom into explosive crystals. Results include developing a simplified mathematical relationship between the electron beam energy and mill rate, assessments of pore quality, and material and machine‐specific optimal milling parameters.

Polarization study of the P-wave charmonium radiative decay into a light vector meson at e+e- collider experiment

Abstract In this work, a formalism is presented for the helicity amplitude analysis of the decays ψ(2S) →γ1χcJ, χcJ→γ2V (V=ρ0, Φ, ω) (the subscript 1,2 is used to distinguish the two radiative photons), and the polarization expressions of the P-wave charmonia χcJ and the vector mesons ρ0, Φ, ω for experimental measurements at Electron-Positron Collider. In addition, we derive the formulae of the angular distributions of the χc1,2→γV to extract the degree of transverse polarization PT of e+e- pairs with symmetric beam energy as well as the ratios of two helicity amplitudes x (in χc1 decays) and x, y (in χc2 decays) representing the relative magnitudes of transverse to longitudinal polarization amplitude, and validate it by performing the Monte Carlo simulation. Finally, the statistical sensitivity of PT, x and y are estimated based on the large ψ(2S) data samples collected at the current and proposed future e+e- collider experiment.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must main tain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd