PHYS01200804001 Sohrab Abbas - Homi Bhabha National Institute

spallation sources yield peak neutron flux of 10 16 cm −2 s −1 and 10 17 cm −2 s −1 [13-15]. New neutron
sources under study, based on inertial confinement fusion (ICF) will increase the neutron flux by
many orders of magnitude (Fig.1) [14]. Neutron sources are inherently weak compared to X-ray
sources. However, due to the importance of neutrons, numerous research reactors have been built
around the world. To mention a few of them, state-of-the-art research reactors like 10 MW BERII
in Helmholtz Zentrum Berlin and 20 MW FRM II in Munich (Germany) [16], 58 MW ILL reactor
in Grenoble (France) [17], 100 MW Dhruva reactor in Mumbai (India) [18], 20 MW NIST [19] and
LANL [20] in USA have been built and are operational. Next-generation spallation neutron source
facilities e.g., SNS at Oak Ridge National Laboratory-U.S.A [21] and J-PARC at Tokai-Japan [22],
have also become functional.
Extraordinary importance conferred to neutrons is due to its use both as a probe and as an object of
Fig.1 Change in thermal neutron flux with time. Since 1970s, the neutron flux in research reactors
got stagnated due to technical limitations over the achievable power density, forcing to look for
new types of neutron sources like spallation, fusion etc. [14].
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