GeV Proton Beam Research Articles

Beam and target optimization for energy production in accelerator driven systems

The new concept of light nuclear beams instead of proton beams for ADS is substantiated. The influence of the target structure on the energy efficiency of 0.5-4 GeV proton beams and 0.25 – 0.5 AGeV light ion beams is studied. The target consists of rods with different composition (metal, oxide, carbide) and different levels of enrichment in order to implement the target with a criticality coefficient of 0.96 -0.97, which ensures safe operation. The cooling with different metals (lead, lead-bismuth eutectic - LBE, and sodium) is compared. The use of converters from very light materials (lithium, beryllium, carbon) and their influence on the neutron spectrum and energy released are analysed.

Spallation Yield of Neutrons Produced in Tungsten and Bismuth Target Bombarded with 0.1 to 3 GeV Proton Beam

In this paper, we investigated a system, is composed of a natural tungsten and bismuth cylindrical targets. The target has been optimized to produce the maximum of neutrons yield with a diameter of 20 cm and varying height from 10 to 80 cm. The target is bombarded with a high-intensity accelerator by a 0.1 to 3 GeV proton beam. The protons are assumed uniformly distributed across the beam of diameter 2 cm. In this work, we have used Monte Carlo method by using MCNP-6 code to simulate spallation neutron yield, neutron spectrum and distribution of the spallation neutrons coming out of the target in the target region. According to the results approving using several simulations for two targets tungsten and bismuth, the difference of spallation neutron yield increases by 8.92% using a bismuth target and for some beam energy 3 GeV.

Resonance-like coherent production of a pion pair in the reaction $pd \rightarrow pd \pi\pi$pd→pdππ in the GeV region

The reaction $p + d \rightarrow p + d + X$ was studied at 0.8-2.0 GeV proton beam energies with the ANKE magnetic spectrometer at the COSY synchrotron storage ring. The proton-deuteron pairs emerging with high momenta, 0.6-1.8 GeV/$c$, were detected at small angles with respect to the proton beam. Distribution over the reaction missing mass $M_x$ reveals a local enhancement near the threshold of the pion pair production specific for the so-called ABC effect. The enhancement has a structure of a narrow bump placed above a smooth continuum. The invariant mass of the $d\pi\pi$ system in this enhancement region exhibits a resonance-like peak at $M_{d\pi\pi} \approx 2.36$ GeV/$c^2$ with the width $\Gamma \approx 0.10$ GeV/$c^2$. A possible interpretation of these features is discussed.

Development of the proton beam monitor based on the thin diamond crystal for the COMET Experiment

In the COMET experiment, it is essential to establish the online monitor that enables to detect few residual protons between consecutive main proton bunches to search for the muon-to-electron( μ - e ) conversion with a sensitivity below 1 0 − 16 . A thin diamond based detector is proposed because of its ideal characteristics. To realise the diamond based residual proton monitor, a noise suppression is essential since the number of electron–hole pairs generated by a single proton is relatively small in a thin diamond ( ∼ 5000 e - h / 100 μ m ). The prototype detector based on a 0.5 mm thick diamond was developed to evaluate the proton counting capability. The beam test using a 30 GeV proton beam was performed with this prototype and the result is reported in this paper.

Space missions: comparison of shielding effectiveness among different materials using 1 GeV protons

The study of materials suitable for radiation protection of astronauts in space missions is always a topic of fundamental importance. This paper shows the results of the comparison of the effectiveness of different materials in cutting down the radiation dose and is intended as a contribution to the search of the most appropriate material for radiation protection against the Solar Particle Events. The physics case deals with the interaction of a 1 GeV proton beam with slabs of different materials having a thickness of 20 g cm−2. The study was conducted with a simulation tool based on the well-known simulation package Geant4. We focus in this work only on impinging protons with the energy of 1 GeV, and not on the whole energy spectrum of Solar Particle Events, because the simulated dose can be easily verified under strict experimental conditions thus providing the benefit of the validation of the prediction capabilities of the simulation tool developed. We conclude that the Nomex material, with the inclusion of a percentage of air, is more efficient than aluminum for what it concerns the shielding of the 1 GeV proton component of the Solar Particle Events.

The European Spallation Source neutrino Super Beam Design Study

The discovery of oscillations and the latest progress in neutrino physics will make possible to observe, for the first time, CP violation in the lepton sector, if it exists. This will help to understand the disappearance of antimatter in the Universe. To go further beyond the current knowledge, it is necessary to develop more and more powerful instruments, but also to combine skills by creating strong international networks between researchers. In this framework, the ESSvSB project proposes to use the proton linac of the European Spallation Source (ESS) currently in construction in Lund (Sweden) to produce a very intense neutrino Super Beam, in parallel with the spallation neutron production. The ESS linac is expected to be fully operational by 2023 delivering 5 MW average power, 2 GeV proton beam, with 2.86 ms long pulses at a rate of 14 Hz. By doubling the pulse rate, an average power of 10 MW can be obtained, providing at the same time 5 MW for the neutron facility and the 5 MW for the production of the neutrino beam. The primary proton beam-line completing the linac will consist of an accumulator ring to compress the beam pulses to 1.3 μs and a switchyard to distribute the protons onto the target station. The secondary beam-line producing neutrinos will consist of a four-horn/target station, a decay tunnel and a beam dump. A megaton scale Water Cherenkov neutrino detector will be located at a baseline of about 500 km in one of the existing mines in Sweden, to measure the neutrino oscillations.

Possible atmospheric-like neutron beams at CSNS

The China Spallation Neutron Source (CSNS) has started commissioning in early 2018. The neutron spectrum from the tungsten target bombarded by a 1.6 GeV proton beam is very wide, namely with characteristics of a white neutron spectrum. In this paper two white neutron beams schemed at CSNS are simulated by using the FLUKA code. And the beam spectrum and intensity are compared with that from other neutron sources in the world. The fidelity for the chip irradiation experiments by using the neutron spectra of these two white-neutron beam lines is estimated. These atmospheric-like neutron beams will be the first white neutron beam lines at CSNS and more intensive ones for carrying out an accelerated test of the neutron-induced single event effect (SEE) will be available in a few years.

Development of a monolithic pixel sensor based on SOI technology for the ILC vertex detector

SOI detector SOFIST is a pixel sensor optimized for the International Linear Collider vertex detector. SOFIST stores both position and timing information of charged particles. Our aim is to achieve 3 μm single-point resolution with a 20 × 20 μm2 pixel. The first prototype sensor SOFIST Ver.1 was evaluated with a 120 GeV proton beam at the FermiLab Test Beam Facility. The position resolution was about 1.3 μm. We are currently evaluating the next version of sensor, SOFIST Ver.2, which has an in-pixel comparator and timestamp.

First Experimental Results on Damage Limits of Superconducting Accelerator Magnet Components Due to Instantaneous Beam Impact

The energy stored in the particle beams of an accelerator such as CERNs LHC is substantial and requires a complex machine protection system to protect the equipment from damage. Despite efficient beam absorbers, several failure modes can lead to beam impact on superconducting magnets. The energy deposition from these beam losses can cause significant temperature rise and mechanical stress in the magnet coils, which can lead to a degradation of the insulation strength and critical current of the superconducting cables. An improved understanding of the damage mechanisms is important for the LHC when considering its planned increase in beam brightness, as well as for other accelerators using superconducting magnets. The degradation mechanisms of Nb-Ti and Nb $_3$ Sn strands and the cable stacks insulation have been assessed based on magnetization and breakdown voltage measurements in three experiments at room temperature. The degradation of the insulation when exposed to high temperatures for several hours was measured. The second experiment assessed the effect of a millisecond temperature rise on superconducting strands using a fast capacitor discharge. In the third experiment, cable stacks and single strands have been exposed to a 440 GeV proton beam. In this paper, the experimental results of these tests are presented and discussed.

Study of neutron shielding collimators for curved beamlines at the European Spallation Source

The European Spallation Source is being constructed in Lund, Sweden and is planned to be the world’s brightest pulsed spallation neutron source for cold and thermal neutron beams (≤ 1 eV). The facility uses a 2 GeV proton beam to produce neutrons from a tungsten target. The neutrons are then moderated in a moderator assembly consisting of both liquid hydrogen and water compartments. Surrounding the moderator are 22 beamports, which view the moderator’s outside surfaces. The beamports are connected to long neutron guides that transport the moderated neutrons to the sample position via reflections. As well as the desired moderated neutrons, fast neutrons coming directly from the target can find their way down the beamlines. These can create unwanted sources of background for the instruments. To mitigate such a kind of background, several instruments will use curved guides to lose direct line-of-sight (LoS) to the moderator and the target. In addition instruments can also use shielding collimators to reduce the amount of fast neutrons further traveling down the guide due to albedo reflections or streaming. Several different materials have been proposed for this purpose. We present the results of a study of different options for collimators and identify the optimal choices that balance cost, background and activation levels.

Review of hydrodynamic tunneling issues in high power particle accelerators

Abstract Full impact of one Large Hadron Collider (LHC) 7 TeV proton beam on solid targets made of different materials including copper and carbon, was simulated using an energy deposition code, FLUKA and a two-dimensional hydrodynamic code, BIG2, iteratively. These studies showed that the penetration depth of the entire beam comprised of 2808 proton bunches significantly increases due to a phenomenon named hydrodynamic tunneling of the protons and the shower. For example, the static range of a single 7 TeV proton and its shower is about 1 m in solid copper, but the full LHC beam will penetrate up to about 35 m in the target, if the hydrodynamic effects were included. Due to the potential implications of this result on the machine protection considerations, it was decided to have an experimental verification of the hydrodynamic tunneling effect. For this purpose, experiments were carried out at the CERN HiRadMat (High Radiation to Materials) facility in which extended solid copper cylindrical targets were irradiated with the 440 GeV proton beam generated by the Super Proton Synchrotron (SPS). Simulations of beam-target heating considering the same beam parameters that were used in the experiments, were also performed. These experiments not only confirmed the existence of the hydrodynamic tunneling, but the experimental measurements showed very good agreement with the experimental results as well. This provided confidence in the work on LHC related beam-matter heating simulations. Currently, a design study is being carried out by the international community (with CERN taking the leading role) for a post LHC collider named, the Future Circular Collider (FCC) which will accelerate two counter rotating proton beams up to a particle energy of 50 TeV. Simulations of the full impact of one FCC beam comprised of 10,600 proton bunches with a solid copper target have also been done. These simulations have shown that although the static range of a single 50 TeV proton and its shower in solid copper is around 1.8 m, the entire beam will penetrate up to about 350 m in the target. Feasibility studies of developing a water beam dump for the FCC have also been carried out. A review of this work and its implications on machine protection system are presented in this paper.

Studies of uniformity of 50 [formula omitted]m low-gain avalanche detectors at the Fermilab test beam

In this paper we report measurements of the uniformity of time resolution, signal amplitude, and charged particle detection efficiency across the sensor surface of low-gain avalanche detectors (LGAD). Comparisons of the performance of sensors with different doping concentrations and different active thicknesses are presented, as well as their temperature dependence and radiation tolerance up to 6×1014 n/cm2. Results were obtained at the Fermilab test beam facility using 120 GeV proton beams, and a high precision pixel tracking detector. LGAD sensors manufactured by the Centro Nacional de Microelectrónica (CNM) and Hamamatsu Photonics (HPK) were studied. The uniformity of the sensor response in pulse height before irradiation was found to have a 2% spread. The signal detection efficiency and timing resolution in the sensitive areas before irradiation were found to be 100% and 30–40 ps, respectively. A “no-response” area between pads was measured to be about 130 μm for CNM and 170μm for HPK sensors. After a neutron fluence of 6×1014 n/cm2 the CNM sensor exhibits a large gain variation of up to a factor of 2.5 when comparing metalized and non-metalized sensor areas. An irradiated CNM sensor achieved a time resolution of 30 ps for the metalized area and 40 ps for the non-metalized area, while a HPK sensor irradiated to the same fluence achieved a 30 ps time resolution.

Missing-mass spectroscopy of the C12(p,d) reaction near the η′ -meson production threshold

Excitation-energy spectra of $^{11}$C nuclei near the $\eta^\prime$-meson production threshold have been measured by missing-mass spectroscopy using the $^{12}$C($p$,$d$) reaction. A carbon target has been irradiated with a 2.5 GeV proton beam supplied by the synchrotron SIS-18 at GSI to produce $\eta^\prime$ meson bound states in $^{11}$C nuclei. Deuterons emitted at $0^\circ$ in the reaction have been momentum-analyzed by the fragment separator (FRS) used as a high-resolution spectrometer. No distinct structure due to the formation of $\eta^\prime$-mesic states is observed although a high statistical sensitivity is achieved in the experimental spectra. Upper limits on the formation cross sections of $\eta^\prime$-mesic states are determined, and thereby a constraint imposed on the $\eta^\prime$-nucleus interaction is discussed.

Investigation of spallation neutron production by 1 GeV protons beam

The MCNP code based on the Monte Carlo model is intended for neutron simulations. It is used to study neutron production, neutron flux calculations, energy deposition, dose, and multiplicity of neutrons; in this paper, we used the MCNP6 code for neutron simulation in spallation targets. We are interested in a 1 GeV proton beam that enters frontal impact with several targets; the geometry of all targets is 10 cm in height and 69 cm in radius. The simulations made in this study clearly show that there are no heavy targets (Co, Cd and Fe), but their neutron production rates are remarkable. We also conclude that the selected targets may be useful to handle almost like spallation targets in an accelerator-driven system.

Development of monolithic pixel detector with SOI technology for the ILC vertex detector

We have been developing a monolithic pixel sensor for the International Linear Collider (ILC) vertex detector with the 0.2 μm FD-SOI CMOS process by LAPIS Semiconductor Co., Ltd. We aim to achieve a 3 μm single-point resolution required for the ILC with a 20×20 μm2 pixel. Beam bunch crossing at the ILC occurs every 554 ns in 1-msec-long bunch trains with an interval of 200 ms. Each pixel must record the charge and time stamp of a hit to identify a collision bunch for event reconstruction. Necessary functions include the amplifier, comparator, shift register, analog memory and time stamp implementation in each pixel, and column ADC and Zero-suppression logic on the chip. We tested the first prototype sensor, SOFIST ver.1, with a 120 GeV proton beam at the Fermilab Test Beam Facility in January 2017. SOFIST ver.1 has a charge sensitive amplifier and two analog memories in each pixel, and an 8-bit Wilkinson-type ADC is implemented for each column on the chip. We measured the residual of the hit position to the reconstructed track. The standard deviation of the residual distribution fitted by a Gaussian is better than 3 μm.

SHiP project as a new facility at intensity frontier

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility suggested for SPS accelerator at CERN. The experiment is currently in Comprehensive Design Report preparation phase, aiming to become a part of European Strategy for Particle Physics update in 2019. In the initial phase of SHiP, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target producing 2 × 1020 protons on target in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles and masses below O(10) GeV/c2. The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and Heavy Neutrinos. The sensitivity to Heavy Neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which Baryogenesis and active neutrino masses could be explained simultaneously. Another dedicated detector will allow the study of tau-neutrino physics.

J-PARC accelerator and neutrino beamline upgrade programme

The 30 GeV proton beam from the J-PARC Main Ring (MR) accelerator is used to produce a world-class conventional neutrino beam – the neutrino source for the J-PARC long-baseline neutrino programme, including the current T2K experiment and proposed future experiments. Planned upgrades to increase the beam power of the MR from the current ∼400 kW to the design power of 750 kW and beyond, to 1.3+ MW, are underway. These include hardware modifications, such as upgrades of the MR magnet power supplies, RF systems, and feedback systems, as well as a change of the MR beam betatron tune point. Upgrades to the neutrino beamline, such as to the proton beam monitoring, horns, and radioactive material handling, will also be required to accommodate the increased proton beam power. An overview of planned J-PARC MR and neutrino facility upgrades is given.

SHiP: a new facility with a dedicated detector for studying tau-neutrino properties and nucleon structure functions

SHiP is a new general purpose fixed target facility, whose Technical Proposal has been recently reviewed by the CERN SPS Committee, who recommended that the experiment proceeds further to a Comprehensive Design phase. In its initial phase, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating 2 × 1020 pot in 5 years. A dedicated detector downstream of the target will allow to probe a variety of models with light long-lived exotic particles and masses below a few GeV/c2. Another dedicated detector will allow the study of neutrino cross-sections and angular distributions, which was the focus of the poster. ντ deep inelastic scattering cross sections will be measured with a statistics 1000 times larger than currently available, with the extraction of the F4 and F5 structure functions, never measured so far and allow for new tests of lepton non-universality with sensitivity to BSM physics. Moreover, ντ’s will be distinguished from ’s, thus providing the first observation of the . With νµ scattering it will be possible to reduce by about 50% the current uncertainty on the strange content of the nucleon in the range of the x variable between 0.05 and 0.3, complementary to LHC measurements. The detector will be based on several techniques developed for the OPERA experiment at LNGS.

Neutrino properties determined in the T2K oscillation experiment

The T2K long baseline neutrino oscillation experiment is composed of a near detector at 280 m and a far detector Super-Kamiokande, located 295 km from the source of neutrinos. The 30 GeV proton beam at JPARC is used to produce a beam of mainly muon neutrinos which are directed toward the large Cherenkov detector. The goal of the experiment is oscillation measurements, such as electron neutrino appearance and θ23 mixing angle measurements from muon neutrino disappearance. By reversing the beam polarity antineutrino oscillations may also be studied. Muon antineutrino disappearance and electron antineutrino appearance have been studied with 4×1020 protons on target in antineutrino beam mode. The most recent oscillation results from T2K for neutrinos and antineutrinos are presented here. Future long baseline oscillation projects in short and long time scale are briefly mentioned.

Prospects of direct search for dark photon and dark Higgs in SeaQuest/E1067 experiment at the Fermilab main injector

In this review, we present the current status and prospects of the dark sector physics search program of the SeaQuest/E1067 fixed target dimuon experiment at Fermilab Main Injector. There has been tremendous excitement and progress in searching for new physics in the dark sector in recent years. Dark sector refers to a collection of currently unknown particles that do not directly couple with the Standard Model (SM) strong and electroweak (EW) interactions but assumed to carry gravitational force, thus could be candidates of the missing Dark Matter (DM). Such particles may interact with the SM particles through “portal” interactions. Two of the simple possibilities are being investigated in our initial search: (1) dark photon and (2) dark Higgs. They could be within immediate reach of current or near future experimental search. We show there is a unique opportunity today at Fermilab to directly search for these particles in a highly motivated but uncharted parameter space in high-energy proton–nucleus collisions in the beam-dump mode using the 120 GeV proton beam from the Main Injector. Our current search window covers the mass range 0.2–10 GeV/c2, and in the near future, by adding an electromagnetic calorimeter (EMCal) to the spectrometer, we can further explore the lower mass region down to about [Formula: see text][Formula: see text]1 MeV/c2 through the di-electron channel. If dark photons (and/or dark Higgs) were observed, they would revolutionize our understanding of the fundamental structures and interactions of our universe.