Speaker
Description
Generation of neutrons with lasers has been in the focus of research and development for over two decades. Such neutron sources exhibit unique properties as inherently pulsed operation, ultrashort pulse duration (around and below nanosecond), and small source size. Besides, the driving laser is not a nuclear device, and there are no proliferation issues. Hence, it is an inherently safe pulsed neutron source which capable to produce high flux rate neutrons to a target under examination in a cost effective way.
A laser-based neutron source was developed by the National Laser-Initiated Transmutation Laboratory of the University of Szeged, and commissioned in the Hungarian site of ELI ERIC. Laser pulses from the 1 kHz repetition rate SYLOS3 laser were focused onto an ultrathin heavy water sheet in vacuum. The 80 mJ, sub-10 fs laser pulses accelerated deuterons to a cut-off energy around 2 MeV, which induced a $^2H(d,n)^3H$ fusion reaction in a heavy water flowing sheet as a neutron catcher. The resulting neutrons have a directionality along the propagating direction of the deuteron ions, and a unique feature of quasi-monoenergetic spectrum centered around 3.2 MeV. We maximized the neutron yield per laser shot by tuning the dispersion, and hence the temporal shape of the laser pulse. The average neutron flux was $10^8$ $neutron/
cm^2/s$ on the target, while the peak neutron flux rate of a neutron pulse was estimated close to $10^{13} neutron/cm^2/s$. The system was demonstrated working with a continuous, stable operation (<5% rms) for over 4 hours.
First, a total of 1.6 Gy dose was delivered on zebrafish embryos. The density of apoptotic cells as well as double-strand breaks in the zebrafish embryos was similar to that of the control group irradiated with cyclotron-generated neutrons. However, photomotor responses showed differences.
In a second experiment we explored the viability of laser driven neutron sources to produce theranostics radiopharmaceuticals for imaging and cancer treatment. At present, the demand for the radiopharmaceuticals Lu-177, Tb-161, Cu-67, and Cu-64 is hitting global production limits and a solution needs to be found to increase supply. In this first pilot experiments, we were able to prove the production of Cu-64 with extra high purity. Further analysis of the quality and outcome of these trials is underway.
| Working group | WG6 |
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