The SARAF Phase II cryogenic linear accelerator (linac) is currently under construction and will be commissioned through collaborative efforts between SNRC and CEA. The linac will accelerate a 5 mA pulsed/continuous wave (CW) proton and deuteron beam, reaching energies of up to 35 MeV and 40 MeV, respectively. The linac injector consists of Phase I components, including an ECR ion source, a Low-Energy Beam Transport (LEBT) line, and a 4-rod Radio Frequency Quadruple (RFQ). Additionally, a new Medium Energy Beam Transport (MEBT) line has been installed and integrated into the injector infrastructure. The MEBT includes three rebuncher resonators, magneto-optical elements, and beam diagnostics. The MEBT beam diagnostics, as well as the Phase I D-plate installed downstream, were used for beam characterization. The downstream-installed Temporary Beam Line (TBL) and a prototype of the Gallium Indium Liquid Target (GALIT) were used for commissioning, operating at high beam duty cycles, including CW mode. The report describes the proton beam commissioning process of the injector prior to the delivery of the cryomodules, scheduled for the second half of 2023.

The authors of this study developed a high-power inductive coupler with a high-voltage DC blocker that is capable of delivering up to 100 kW of CW RF power at 176 MHz and 4 kV DC. The high-power indictive coupler was developed at the Soreq Nuclear Research Center for the radio-frequency quadrupole of the Soreq Applied Research Accelerator Facility. The purpose of the DC blocker is to enable the application of high-voltage DC bias to the inner conductors of the couplers in order to prevent the multipacting phenomena. A new, mechanically and thermally improved, version of the RF coupler is designed and implemented in conjunction with the DC blocker. The underlying design principles, indigenous development, and results of tests of the coupler are presented here.

High power high voltage bias-T units capable of delivering up to 100 kW CW RF power at 176 MHz and up to 4 kV DC were developed at the Soreq Nuclear Research Center for the Soreq Applied Research Accelerator Facility linac. Two separate bias-T units with different requirements were designed for the radio frequency quadrupole couplers and the half wave resonator couplers. The purpose of this bias-T is to prevent multipacting phenomena by application of a high voltage DC bias to inner conductors of RF couplers. Underlying design principles, indigenous development, and successful off-line and on-line tests results are presented.

A fast chopper system has been developed for single-bunch selection for Phase I of the Soreq Applied Research Accelerator Facility (SARAF) in Israel. Further upgrade of the fast chopper system has improved its performance by enabling single-bunch selection for protons and deuterons at a repetition rate up to 220 kHz, with bunch transmission of up to 65% and with neighboring bunch contamination of less than 15%. The upgrade included (1) the redesign of the chopper deflection plates to minimize the electric-field asymmetry and provide more effective single-bunch selection, (2) a new trigger system with better trigger time resolution and better control capabilities, (3) an upgrade of the chopper electronics to increase the repetition rate, (4) the design of the chopper machine protection system, and (5) a general upgrade of the chopper concept to allow for operation in fast and slow modes. The implemented upgrades and the performance of the upgraded system are described. In addition, examples of the first experiments using the neutron time-of-flight (TOF) technique are presented. A fast neutron TOF facility, based on the upgraded fast chopper, is planned for SARAF Phase II. The high neutron flux at SARAF Phase II combined with the upgraded fast chopper system will make SARAF competitive with other advanced neutron research facilities.

The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Research Accelerator Facility (SARAF) injector and must be able to operate at RF powers up to 190 kW continuous wave and transport 5 mA proton and deuteron beams. The SARAF Phase I RFQ is planned for use in Phase II. The period between the termination of Phase I and the installation of Phase II provided an opportunity to introduce RFQ improvements to fully meet the Phase II requirements. These upgrades and improvements are presented in this report together with the results of the recent conditioning campaigns.

Compact narrow-band high power Solid State Power Amplifiers (SSPA) capable of delivering up to 10/20 kW CW RF power at 176 MHz were developed at SNRC for SARAF Linac Phase II. The 10/20 kW amplifiers were built by combining RF power from two/four 5 kW high power amplifiers using 3 dB 0-90 High Power Quad Hybrid Couplers (HPQHC). In their turn, the 5 kW amplifiers were combined from eight LDMOS water cooled amplifiers modules equipped with internal circulators and RF loads. The total power gain of the 10/20 kW amplifiers (including the driver stages) is 70/73 dB. These amplifiers have the ability to withstand with continuous wave full reflection power (VSWR at nominal rating > 100:1) for a long time without the use of an external circulator. Unconditional stability for CW and pulsed operation, reliability, linearity, high efficiency, simple design and compact size are the main features we sought for this amplifier. The underlying design principles, indigenous development and test results are presented.

This paper demonstrates that that nuclear track detectors made of CR39 plates are suitable for detecting low energy protons and alpha-particles. The authors present evidence for a background line that arises from the interaction of neutrons with ${}^{17}$O inside the CR39 plate. This can be used for self-calibration of the CR39 detector

Knowledge of the neutron capture of copper and cobalt isotopes is important for the understanding of abundances of the heavier elements produced via the weak $s$ process. There are considerable discrepancies for the $^{63}\mathrm{Cu}(n,\ensuremath{\gamma})^{64}\mathrm{Cu}$ and $^{65}\mathrm{Cu}(n,\ensuremath{\gamma})^{66}\mathrm{Cu}$ cross-section values in the literature. New measurements of these cross sections were performed at the SARAF phase I facility using a high-power quasi-Maxwellian neutron source produced by irradiation of the liquid-lithium target (LiLiT) with an intense continuous-wave proton beam. The cross sections were measured by counting the activity of the irradiated targets. The measurement allowed us to evaluate the $^{63}\mathrm{Cu}(n,\ensuremath{\gamma})^{64}\mathrm{Cu}$, $^{65}\mathrm{Cu}(n,\ensuremath{\gamma})^{66}\mathrm{Cu}$, and $^{59}\mathrm{Co}(n,\ensuremath{\gamma})^{60}\mathrm{Co}$ Maxwellian averaged cross sections at 30 keV, obtaining values of $70.4\ifmmode\pm\else\textpm\fi{}1.{8}_{\mathrm{exp}}\ifmmode\pm\else\textpm\fi{}2.{4}_{\mathrm{syst}}$, $26.8\ifmmode\pm\else\textpm\fi{}1.{5}_{\mathrm{exp}}\ifmmode\pm\else\textpm\fi{}1.{0}_{\mathrm{syst}}$, and $38.1\ifmmode\pm\else\textpm\fi{}0.{9}_{\mathrm{exp}}\ifmmode\pm\else\textpm\fi{}0.{9}_{\mathrm{syst}}\phantom{\rule{0.16em}{0ex}}\mathrm{mb}$, respectively. The results are compared with previous measurements in the literature.

Knowledge of the neutron capture of copper and cobalt isotopes is important for the understanding of abundances of the heavier elements produced via the weak s process. There are considerable discrepancies for the Cu-63(n, gamma)Cu-64 and Cu-65(n, gamma)Cu-66 cross-section values in the literature. New measurements of these cross sections were performed at the SARAF phase I facility using a high-power quasi-Maxwellian neutron source produced by irradiation of the liquid-lithium target (LiLiT) with an intense continuous-wave proton beam. The cross sections were measured by counting the activity of the irradiated targets. The measurement allowed us to evaluate the Cu-63(n, gamma)Cu-64, Cu-65(n, gamma)Cu-66, and Co-59(n, gamma)Co-60 Maxwellian averaged cross sections at 30 keV, obtaining values of 70.4 +/- 1.8(exp) +/- 2.4(syst), 26.8 +/- 1.5(exp) +/- 1.0(syst), and 38.1 +/- 0.9(exp) +/- 0.9(syst) mb, respectively. The results are compared with previous measurements in the literature.

Soreq Nuclear Research Center (SNRC) and CEA collaborate for the upgrade of the existing Soreq Applied Research Accelerator Facility (SARAF) accelerator up to 5mA Continuous Wave (CW) 40 MeV deuteron and proton beams (Phase 2). SNRC is upgrading the injector: the ion source, the low energy beam transport line and the 4-rods Radio Frequency Quadrupole (RFQ). CEA is in charge of the development and commissioning of the medium energy beam transport line and the superconducting linac. This paper presents the status of the SARAF linac development by CEA and the installation and testing of a new set of rods electrodes in the SARAF RFQ.

SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the MEBT line and the superconducting linac (SARAF-LINAC Project). The prototypes of the 176 MHz NC rebuncher, SC cavities, RF coupler and SC solenoid-Package have been tested recently. Meanwhile, the cryomodules technical specifications have been written and called for tender. This paper presents the status of the SARAF-LINAC Project at April 2019.

Single and polycrystalline tungsten samples were irradiated with 2.2 MeV protons at Soreq Applied Research Accelerator Facility (SARAF). Hydrogen blisters were obtained for both single crystal and polycrystalline samples, elucidating the role of grain boundaries in blister formation. The effect of temperature and flux on the critical formation dose for blisters and on their dimensions was studied. It was found that for single crystals, the critical formation dose is one order of magnitude higher than for polycrystalline tungsten at high temperature irradiation conditions. Upon reducing the irradiation temperature to ambient, the critical dose for formation of blisters in single crystals was reduced by a factor of three while in polycrystalline tungsten there was no significant change with temperature, thus indicating the role of grain boundaries in blister formation. Larger blisters were obtained in single crystals than in polycrystalline tungsten at ambient temperature conditions, identifying the grain boundaries as a preferential additional hydrogen trap. The height to area ratio of the blisters is found to be strongly temperature dependent and only weakly dependent on irradiation flux for both single and polycrystalline samples. (C) 2018 Elsevier B.V. All rights reserved.

A strong effect of the 176 MHz RF field on the low energy beam optics was observed at the SARAF RFQ/LEBT interface. The effect was studied for various LEBT proton beam energies and for the broad range of RE field amplitudes. The measurements and simulations suggest that, most likely, the effect is associated with loss of the beam neutralization in the LEBT region adjacent to RFQ due to penetration of the field in this region. The effect is partially responsible for reduction in the RFQ injector transmission.

The original SARAF 3.8 m long 4-rod Radio Frequency Quadrupole (RFQ) has been successful in acceleration of 4 mA ContinuousWave (CW) proton beam and pulsed deuteron beam to 1.5 MeV/u. However, conditions for running CW deuteron beam have not been achieved in the original design. A new 4-rod structure has been designed and implemented, with the goal of reducing the RF power required for CW deuteron operation while slightly compromising the RFQ exit energy to 1.27 MeV/u. The new 4-rod structure was manufactured, and installed in place of the old rod electrodes. Superior field homogeneity was achieved. The RFQ was successfully conditioned to the RF power 200 kW required for CW deuteron operation, with sufficient power margin. The commissioning with proton and deuteron beams showed that most of beam parameters are close to the designed specifications. The first operation with CW RF power of 5 mA deuteron beam was demonstrated. In addition, a 1.1 mA CW deuteron beam was transported through the superconducting module. The future scope of RFQ improvements is discussed.

A new version of a beam dump was tested at SARAF Phase I. The beam dump consisted of a grid of tungsten pins welded to water-cool copper backing. The beam-induced heat was dissipated mainly through thermal radiation with a smaller amount via thermal conductance. Beam rastering was performed for better control of the irradiated area and beam density. A test irradiation using a 4 kW protons beam power demonstrated that the current design could readily accept average 300 W/cm(2) beam power density while achieving low prompt and residual radiation levels with no blistering damage. Local melting of pins was observed at beam power density of 800 W/cm(2). The results of the irradiation test are presented and analyzed and the plans for future improvements are discussed.

Bismuth capture of neutrons is the termination point of the s-process cycle of nucleosynthesis in stellar environments. A new measurement is reported here for neutron activation of bismuth with an intense quasi-Maxwellian neutron source at kT similar to 30 keV. The measurement was performed at the SARAF phase I accelerator facility by bombarding a 1.5-mA proton beam on the liquid-lithium larget. The cross section of the Bi-209(n,gamma) capture reaction leading to the Bi-210 ground state was determined by combining beta measurements from the Bi-210g decay and a and. from the subsequent Po-210 decay, along with detailed Monte Carlo simulations of the Li-7(p,n) reaction kinematics and the activation experimental setup. Deduced Maxwellian averaged cross sections (MACS) for Bi-209(n,gamma)(210g) Bi at kT = 30 keV using the ENDF, JEFF, and JENDL databases for the corrections and extrapolations yielded a value of 1.84 +/- 0.09 mb. A comparison is made with previous measurements, including time-of-flight (TOF) measurements of the total bismuth capture cross section. Plans for obtaining the MACS for capture to the bismuth-210 metastable state in the reaction Bi-209(n,gamma)Bi-210m are discussed, along with estimates based on our results in comparison with TOF measurements. The bismuth neutron activation cross section is also of importance for design of GenIV reactor coolant and subcritical accelerator driven systems, especially in light of the 3 million year half-life of the Bi-210m isomer.

The SARAF 176 MHz accelerator is designed to provide CW proton/deuteron beams up to 5 mA current and 40 MeV accelerated ion energy. Phase I of SARAF (up to 4–5 MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the design and first prototyping stage and will contain longer MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3 MeV/u RFQ, is 4.5 m long, and contains three 176 MHz rebunchers providing a field integral of 105 kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with the 40 mm diameter required by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.

The doubly magic $^{208}\mathrm{Pb}$ nucleus is a bottleneck at the termination of the $s$-process path due to its very low neutron capture cross section. This cross section is also important for the decomposition of $s$, $r$ processes and U/Th radiogenic decay contributions to the Pb-Bi solar abundances. The $^{208}\mathrm{Pb}(n,\ensuremath{\gamma})^{209}\mathrm{Pb}$ cross section was measured at the Soreq Applied Research Accelerator Facility Phase I using an intense quasi-Maxwellian neutron source produced by irradiation of the liquid-lithium target with a 1.5-mA continuous-wave proton beam at 1.94 MeV. The cross section was measured by counting the $\ensuremath{\beta}$ activity from the irradiated lead target. The measurement allowed us to evaluate the Maxwellian averaged cross section (MACS) at 30 keV obtaining a value of 0.33(2) mb. This has been compared with the earlier activation and time-of-flight measurements found in the literature. The MACS cross-sectional value of the $^{63}\mathrm{Cu}(n,\ensuremath{\gamma})^{64}\mathrm{Cu}$ reaction was determined in the same experiment and is compared to a recent published value.