The Meson Production Targets in the high energy beamline of HIPA at PSI

Two target stations in the 590 MeV proton beamline of the High Intensity Proton Accelerator (HIPA) at the Paul Scherrer Institut (PSI) produce pions and muons for seven secondary beamlines, leading to several experimental stations. The two target stations are 18 m apart. Target M is a graphite target with an effective thickness of 5 mm, Target E is a graphite wheel with a thickness of 40 mm or 60 mm. Due to the spreading of the beam in the thick target, a high power collimator system is needed to shape the beam for further transport. The beam is then transported to either the SINQ target, a neutron spallation source, or stopped in the beam dump, where about 450 kW beam power is dissipated. Targets, collimators and beam dumps are described.

MBGEM: a stack of borated GEM detector for high efficiency thermal neutron detection

A new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to today’s standard $$^3\mathrm{He}$$ 3 He -based technology for application to thermal neutron scattering. The key elements of the development are the boron-coated GEM foils (Sauli in Nucl Instrum Methods Phys Res Sect A Accel Spectrom Detect Assoc Equip 386:531, 1997) that are used as a multi-layer neutron converter via the $$^{10}\mathrm{B}(n,\alpha )^7\mathrm{Li}$$ 10 B ( n , α ) 7 Li reaction together with an efficient collection of the produced secondary electrons. This paper reports the test performed on a 3 layers converter prototype coupled to a GEMPix detector (Murtas in Radiat Meas 138:106421, 2020), carried out in order to study the possibility to produce a large-scale multi-layer neutron detector capable to reach high detection efficiency with high spatial resolution and able to sustain the high neutron flux expected in the new neutron spallation source under development like the ESS.

NEURAP—A Dedicated Neutron-Imaging Facility for Highly Radioactive Samples

NEURAP is a dedicated set-up at the Swiss neutron spallation source (SINQ) at the Paul Scherrer Institut (PSI), optionally implemented as a special configuration of the neutron-imaging station NEUTRA. It is one of very few instrumentations available worldwide enabling neutron-imaging of highly radioactive samples to be performed routinely, with special precautions and following a specific procedure. Since the relevant objects are strong γ-sources, dedicated techniques are needed to handle the samples and to perform neutron-imaging despite the radiation background. Dysprosium (Dy)-loaded imaging plates, effectively made sensitive to neutrons only, are employed. Neutrons are captured by Dy during neutron irradiation. Then the imaging plate is erased removing gamma detections. A subsequent relatively long self-exposure by the radiation from the intrinsic neutron-activated Dy within the imaging plate yields the neutron-only radiograph that is finally read out. During more than 20 years of NEURAP operation, images have been obtained for two major applications: (a) highly radioactive SINQ target components were investigated after long-term operation life; and (b) spent fuel rods and their cladding from Swiss nuclear power plants were characterized. Quantitative analysis of the image data demonstrated the accumulation of spallation products in the lead filled “Cannelloni” Zircaloy tubes of the SINQ target and the aggregation of hydrogen at specific sites in used fuel pins of power plants and their cladding, respectively. These results continue to help understanding material degradation and optimizing the operational regimes, which might lead to extending the safe lifetimes of these components.

From nuclear astrophysics to fundamental nuclear physics: challenging experimental approaches at n_TOF (CERN)

The n_TOF installation at CERN is one of the leading neutron facilities worldwide undergoing a major update of the neutron spallation source. The update will provide improved n-TOF resolution in the experimental areas and the possibility to perform neutron cross section measurements at very high neutron flux (NEAR-Station). The renewed capabilities of the facility must be supported by smart and non-conventional experimental approaches. In this framework two examples will be reported. The first one concerns the measurement of a key reaction channel involved in Primordial Nucleosynthesis: the 7Be(n, α), by using a radioactive 7Be target. The second one provides a state-of-the-art scenario for the n-n scattering length measurement. This will be performed by neutron-deuteron (n-d) breakup three-body reaction. In this case, the envisaged experimental setup will provide a complete three-body kinematic reconstruction. By these important physics cases we are crossing the technological frontiers for charged particle and neutron detection.

4D Bragg Edge Tomography of Directional Ice Templated Graphite Electrodes

Bragg edge tomography was carried out on novel, ultra-thick, directional ice templated graphite electrodes for Li-ion battery cells to visualise the distribution of graphite and stable lithiation phases, namely LiC12 and LiC6. The four-dimensional Bragg edge, wavelength-resolved neutron tomography technique allowed the investigation of the crystallographic lithiation states and comparison with the electrode state of charge. The tomographic imaging technique provided insight into the crystallographic changes during de-/lithiation over the electrode thickness by mapping the attenuation curves and Bragg edge parameters with a spatial resolution of approximately 300 µm. This feasibility study was performed on the IMAT beamline at the ISIS pulsed neutron spallation source, UK, and was the first time the 4D Bragg edge tomography method was applied to Li-ion battery electrodes. The utility of the technique was further enhanced by correlation with corresponding X-ray tomography data obtained at the Diamond Light Source, UK.

Design of the third-generation neutron spallation target for the CERN’s n_TOF facility

The neutron Time-Of-Flight (n_TOF) facility at the European Laboratory for Particle Physics (CERN) is a pulsed white-spectrum neutron spallation source producing neutrons for two experimental areas: EAR1, located 185 m downstream of the spallation target, and EAR2, located 20 m above the target. The facility is based on a lead target impacted by a high-intensity 20 GeV/c proton beam. It is designed to study neutron-nucleus interactions for neutron kinetic energies from a few meV to several GeV, with applications in nuclear astrophysics, nuclear technology, and medical research. The facility is undergoing a major upgrade in 2019–2020, which will include the installation of the new third-generation target. The second-generation target consists in a water-cooled lead cylinder, while the new target will be cooled by nitrogen to avoid erosion-corrosion phenomena and contamination of the cooling water with radioactive lead spallation products. The new design will be optimized also for the vertical flight path. The operation of the new spallation target will start in 2021. This paper presents an overview on the evolution of the design and on the related R&D activities (including beam irradiation tests) carried out to ensure the best performance for both experimental areas and avoid the contamination issues of the previous targets.

Short-Pulse Laser-Driven Moderated Neutron Source

Neutron production with laser-driven neutron sources was demonstrated. We outline the basics of laser-driven neutron sources, highlight some fundamental advantages, and quantitatively compare the neutron production at the TRIDENT laser sources with the well-established LANSCE pulsed neutron spallation source. Ongoing efforts by our team to continue development of these sources, in particular the LANSCE-ina-box instrument, are described. The promise of ultra-intense lasers as drivers for brilliant, compact, and highly efficient particle accelerators portends driving next-generation neutron sources, potentially replacing in some cases much larger conventional accelerators.

Engineering Design Integration & Non-Destructive Testing for the ESS accelerator

The ESS linac is under construction by the ESS partner institutes (so- called In-Kind Contributors - IKC) and will operate the most powerful proton beam ever for neutron spallation source. The linac delivers 5 MW via 2 GeV protons at a repetition rate of 14 Hz at the He-cooled solid tungsten target. The pulsed neutrons, result of the spallation, will reach the science instruments after having been moderated. The engineering effort needed to assemble the linac and its RF sources (klystrons), commenced with the design integration and currently is undergoing installation planning. In addition, the first dedicated engineering properties experiments, so-called Non-Destructive Testing for Accelerators (NDTA), take place to map and pilot the innovative testing strategy for the ESS linac structural materials. The Engineering Resources Group (ERG) of the Accelerator Division (AD) has been created to provide services of design integration, mechanical engineering and system engineering to ESS Accelerator Systems (ACCSYS) that are applicable across work package boundaries and principles of the linac systems. In parallel, part of the machine integration is the physical plant coordination and supervision. At last, in order to fulfill the missions of feasibility and planning, the ERG designs and leads the development of the technical laboratories for the accelerator systems. The current citation describes the engineering proposal for the mechanical design study and integration of the linac machine, its non- destructive testing and the essential development of the technical areas to service the long-term operational needs.

Isothermal equation of state and high-pressure phase transitions of synthetic meridianiite (MgSO4·11D2O) determined by neutron powder diffraction and quasielastic neutron spectroscopy

We have collected neutron powder diffraction data from MgSO4·11D2O (the deuterated analogue of meridianiite), a highly hydrated sulfate salt that is thought to be a candidate rock-forming mineral in some icy satellites of the outer solar system. Our measurements, made using the PEARL/HiPr and OSIRIS instruments at the ISIS neutron spallation source, covered the range 0.1 < P < 800 MPa and 150 < T < 280 K. The refined unit-cell volumes as a function of P and T are parameterized in the form of a Murnaghan integrated linear equation of state having a zero-pressure volume V 0 = 706.23 (8) Å3, zero-pressure bulk modulus K 0 = 19.9 (4) GPa and its first pressure derivative, K′ = 9 (1). The structure's compressibility is highly anisotropic, as expected, with the three principal directions of the unit-strain tensor having compressibilities of 9.6 × 10−3, 3.4 × 10−2 and 3.4 × 10−3 GPa−1, the most compressible direction being perpendicular to the long axis of a discrete hexadecameric water cluster, (D2O)16. At high pressure we observed two different phase transitions. First, warming of MgSO4·11D2O at 545 MPa resulted in a change in the diffraction pattern at 275 K consistent with partial (peritectic) melting; quasielastic neutron spectra collected simultaneously evince the onset of the reorientational motion of D2O molecules with characteristic time-scales of 20–30 ps, longer than those found in bulk liquid water at the same temperature and commensurate with the lifetime of solvent-separated ion pairs in aqueous MgSO4. Second, at ∼ 0.9 GPa, 240 K, MgSO4·11D2O decomposed into high-pressure water ice phase VI and MgSO4·9D2O, a recently discovered phase that has hitherto only been formed at ambient pressure by quenching small droplets of MgSO4(aq) in liquid nitrogen. The fate of the high-pressure enneahydrate on further compression and warming is not clear from the neutron diffraction data, but its occurrence indicates that it may also be a rock-forming mineral in the deep mantles of large icy satellites.