Ido Silverman

High-power liquid-lithium target prototype for accelerator-based boron neutron capture therapy

A prototype of a compact Liquid-Lithium Target (LiLiT), which will possibly constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals, was built. The LiLiT setup is presently being commissioned at Soreq Nuclear Research Center (SNRC). The liquid-lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power generated using a high-intensity proton beam (>10 kW), necessary for sufficient neutron flux. In off-line circulation tests, the liquid-lithium loop generated a stable lithium jet at high velocity, on a concave supporting wall; the concept will first be tested using a high-power electron beam impinging on the lithium jet. High intensity proton beam irradiation (1.91-2.5 MeV, 2-4 mA) will take place at Soreq Applied Research Accelerator Facility (SARAF) superconducting linear accelerator currently in construction at SNRC. Radiological risks due to the (7)Be produced in the reaction were studied and will be handled through a proper design, including a cold trap and appropriate shielding. A moderator/reflector assembly is planned according to a Monte Carlo simulation, to create a neutron spectrum and intensity maximally effective to the treatment and to reduce prompt gamma radiation dose risks.

High-power electron beam tests of a liquid-lithium target and characterization study of 7Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy

A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors.

The Soreq Applied Research Accelerator Facility (SARAF) - Overview, Research Programs and Future Plans

Abstract.The Soreq Applied Research Accelerator Facility (SARAF) is under construction in the Soreq Nuclear Research Center at Yavne, Israel. When completed at the beginning of the next decade, SARAF will be a user facility for basic and applied nuclear physics, based on a 40 MeV, 5 mA CW proton/deuteron superconducting linear accelerator. Phase I of SARAF (SARAF-I, 4 MeV, 2 mA CW protons, 5 MeV 1 mA CW deuterons) is already in operation, generating scientific results in several fields of interest. The main ongoing program at SARAF-I is the production of 30 keV neutrons and measurement of Maxwellian Averaged Cross Sections (MACS), important for the astrophysical s-process. The world leading Maxwellian epithermal neutron yield at SARAF-I (

Scientific opportunities at SARAF with a liquid lithium jet target neutron source

5 \times 10^{10}

Demonstration of a high-intensity neutron source based on a liquid-lithium target for Accelerator based Boron Neutron Capture Therapy.

5×1010 epithermal neutrons/s), generated by a novel Liquid-Lithium Target (LiLiT), enables improved precision of known MACSs, and new measurements of low-abundance and radioactive isotopes. Research plans for SARAF-II span several disciplines: precision studies of beyond-Standard-Model effects by trapping light exotic radioisotopes, such as 6He, 8Li and 18, 19, 23Ne, in unprecedented amounts (including meaningful studies already at SARAF-I); extended nuclear astrophysics research with higher energy neutrons, including generation and studies of exotic neutron-rich isotopes relevant to the rapid (r-) process; nuclear structure of exotic isotopes; high energy neutron cross sections for basic nuclear physics and material science research, including neutron induced radiation damage; neutron based imaging and therapy; and novel radiopharmaceuticals development and production. In this paper we present a technical overview of SARAF-I and II, including a description of the accelerator and its irradiation targets; a survey of existing research programs at SARAF-I; and the research potential at the completed facility (SARAF-II).

A liquid-lithium target project for production of high-intensity quasi-stellar neutrons

SARAF (Soreq Applied Research Accelerator Facility) is based on a 5 mA, 40 MeV, proton/deuteron accelerator. Phase-I, operational since 2010, provides proton and deuteron beams up to 4 and 5 MeV, respectively, for basic and applied research activities. The high power Liquid-Lithium jet Target (LiLiT), with 1.912 MeV proton beam, provides high flux quasi-Maxwellian neutrons at kT ~30 keV (about 2 × 1010 n/s/cm2/mA on the irradiated sample, about 1 cm from the target), enabling studies of s-process reactions relevant to nucleo-synthesis of the heavy elements in giant AGB stars. With higher energy proton beams and with deuterons, LiLiT can provide higher fluxes of high energy neutrons up to 20 MeV. The experimental program with SARAF phase-I will be enhanced shortly with a new target room complex which is under construction. Finally, SARAF phase-II, planned to start operation at ~2023, will enable full capabilities with proton/ deuteron beams at 5 mA and 40 MeV. Liquid lithium targets will then be used to produce neutron sources with intensities of 1015 n/s, which after thermalization will provide thermal neutron (25 meV) fluxes of about 1012 n/s/cm2 at the entrance to neutron beam lines to diffraction and radiography stations.SARAF (Soreq Applied Research Accelerator Facility) is based on a 5 mA, 40 MeV, proton/deuteron accelerator. Phase-I, operational since 2010, provides proton and deuteron beams up to 4 and 5 MeV, respectively, for basic and applied research activities. The high power Liquid-Lithium jet Target (LiLiT), with 1.912 MeV proton beam, provides high flux quasi-Maxwellian neutrons at kT ~30 keV (about 2 × 1010 n/s/cm2/mA on the irradiated sample, about 1 cm from the target), enabling studies of s-process reactions relevant to nucleo-synthesis of the heavy elements in giant AGB stars. With higher energy proton beams and with deuterons, LiLiT can provide higher fluxes of high energy neutrons up to 20 MeV. The experimental program with SARAF phase-I will be enhanced shortly with a new target room complex which is under construction. Finally, SARAF phase-II, planned to start operation at ~2023, will enable full capabilities with proton/ deuteron beams at 5 mA and 40 MeV. Liquid lithium targets will then be used to pr...

Research Programs And Plans At The Soreq Applied Research Accelerator Facility - SARAF

A free surface liquid-lithium jet target is operating routinely at Soreq Applied Research Accelerator Facility (SARAF), bombarded with a ~1.91 MeV, ~1.2 mA continuous-wave narrow proton beam. The experiments demonstrate the liquid lithium target (LiLiT) capability to constitute an intense source of epithermal neutrons, for Accelerator based Boron Neutron Capture Therapy (BNCT). The target dissipates extremely high ion beam power densities (>3 kW/cm(2), >0.5 MW/cm(3)) for long periods of time, while maintaining stable conditions and localized residual activity. LiLiT generates ~3×10(10) n/s, which is more than one order of magnitude larger than conventional (7)Li(p,n)-based near threshold neutron sources. A shield and moderator assembly for BNCT, with LiLiT irradiated with protons at 1.91 MeV, was designed based on Monte Carlo (MCNP) simulations of BNCT-doses produced in a phantom. According to these simulations it was found that a ~15 mA near threshold proton current will apply the therapeutic doses in ~1h treatment duration. According to our present results, such high current beams can be dissipated in a liquid-lithium target, hence the target design is readily applicable for accelerator-based BNCT.

Nucleosynthesis Reactions With The High-intensity Saraf-lilit Neutron Source

A windowless Liquid-Lithium Target (LiLiT) is under construction and development at Soreq NRC (Israel). The target is designed to be bombarded by a 2-4 mA proton beam (Ep= 1.8-2.5 MeV) from the high-intensity Soreq Applied Research Accelerator Facility (SARAF), a superconducting linear accelerator for light ions. The liquid-lithium forced flow at a velocity of ~20 m/s and a thickness of ~1.8 mm serves both as a power dump (10 kW) for the proton beam and as a neutron-producing target via the 7 Li(p,n) 7 Be reaction. As known from the work of the Forschungszentrum Karlsruhe group, the energy distribution of neutrons emitted for a proton energy Ep= 1.912 MeV, ~30 keV above the reaction threshold, and a thick Li target is very similar to that of a Maxwell-Boltzmann flux at a thermal energy of ~25 keV, well suited for activation measurements relevant to s-process nucleosynthesis. The neutron intensity expected under these conditions from the combination of the SARAF proton beam and the LiLiT thermal properties is of ~2×10 10 s -1 mA -1 , and is larger by more than one order of magnitude than currently available. The LiLiT setup is built as a loop circulating liquid lithium at a temperature of ~200 o C and producing a jet (acting as the target) onto a thin concave supporting wall, driven by a rotating magnet inductive electromagnetic pump. The liquid lithium is collected in a reservoir housing a heat exchanger with a mineral-oil closed loop. Circulation and thermal tests of the loop are presently in progress in an offline dedicated electron-gun laboratory and online installation at the SARAF accelerator is planned for end 2010. Characterization of the SARAF proton beam (beam energy, energy width and transverse profile) and of the neutron spectrum obtained under these conditions are studied in parallel using a solid-lithium (lithium fluoride) target at low beam intensities. The SARAF-LiLiT system will be used to measure stellar neutron capture cross sections for stable or radioactive targets demanding high neutron fluxes. Present status and plans are discussed.

FIRST NUCLEAR-ASTROPHYSICS EXPERIMENTS WITH HIGH-INTENSITY NEUTRONS FROM THE LIQUID-LITHIUM TARGET LiLiT

The Soreq Applied Research Accelerator Facility (SARAF) is under construction at the Soreq Nuclear Research Center, Yavne, Israel. When completed at the beginning of the next decade, SARAF will be a user facility based on a 40 MeV, 5 mA CW proton/deuteron superconducting linear accelerator. Phase I of SARAF (4 MeV, 2 mA CW protons, 5 MeV 1 mA pulsed deuterons) is already in operation. By use of a novel liquid lithium jet target (LiLiT), we generated up to 5×10^10 epithermal neutrons/sec, mainly for nuclear astrophysics research of slow neutron capture processes (s-process). We present a survey of research programs and plans at the completed SARAF, which span several disciplines: Precision studies of beyond-Standard-Model effects by trapping light exotic isotopes, such as 6He, 8Li and Ne isotopes, in unprecedented amounts (including meaningful studies already at Phase I); extended nuclear astrophysics research with higher energy neutrons, including generation and studies of exotic neutron-rich isotopes relevant to the rapid (r-) process; high energy neutrons cross section measurements for basic nuclear physics and material science research, including neutron induced radiation damage; neutron based imaging and therapy; and novel radio-pharmaceuticals development and production.

Method And System For Production Of Radioisotopes, And Radioisotopes Produced Thereby

We present a status report of recent neutron capture experiments performed with the mA-proton beam (1.92 MeV, 3 kW) of the Soreq Applied Research Accelerator Facility (SARAF) and the Liquid-Lithium Target (LiLiT). Experiments and preliminary results for (n,gamma) reactions on 36,38Ar, studied for the first time with 30-keV neutrons, on natKr, natCe and on radioactive targets 147Pm and 171Tm are described.