LXXI International conference "NUCLEUS – 2021. Nuclear physics and elementary particle physics. Nuclear physics technologies"

POSSIBILITY FOR SEPARATING A SHORT-LIVED COMPONENT (T1/2 = 1 ms) IN TOTAL QUANTITY OF DELAYED NEUTRONS FROM PHOTOFISSION OF 238U AT REGISTRATION BETWEEN ELECTRON LINAC PULSES

Not scheduled

25m

Oral report Section 2. Experimental and theoretical studies of nuclear reactions. Section 2. Experimental and theoretical studies of nuclear reactions

Speaker

Dzhilavyan L.Z. 1 (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia)

Description

Fission of actinide nuclei produces fast neutrons, mainly “prompt” neutrons (PNs), but also (2%) “delayed” neutrons (DNs with different half-lives T1/2). Usually, for the sake of convenience, DNs are divided into 6–8 groups according to their T1/2-values at approximately 0.2 s < T1/2 < 56 s (see, e.g., [1]). But there are some indications that it is necessary to search for short-lived DNs with T1/2 down to 1 ms (see, e.g., [2]).
In previous works [3–5], we tried to find such short-lived DN-components in time intervals between pulses of the linear electron accelerator LUE-8-5 of the INR RAS [6] at the incident electron energy Ee = 10 MeV, the duration of each beam pulse 3 (10^-6)s, and their repetition rates (50–300)s(^-1). As we showed in [4], under such conditions, after about 7 min of irradiation with beam with stable parameters, flux of all DNs with 0.2 s < T1/2 < 56 s will be almost constant at an aggregated saturation level (except for some statistical fluctuations). Under these conditions, the sought short-lived component of DNs will give an addition to this level which will decrease exponentially with increasing of t – time after beam pulse (from t = t0 – start of each measuring interval).
In the present work, we considered possibility for separating a short-lived component with T1/2 = 1 ms from total quantity of DNs at photofission of 238U in dependence on as characteristics of DNs (namely, ai – the relative part of the i-th group of delayed neutrons), as characteristics of used registration process (values of t0 and levels of accumulated “statistics”).

1. V.M.Piksaikin, et al., Voprosy Atomnoy Nauki i Tekhniki. Seriya: Yaderno-reaktornye konstanty. Vypusk 1. P. 184 (2019).
2. S.B.Borzakov, et al., Study of Delayed Neutron Decay Curves at Fission of 235U and    239Pu by Thermal Neutrons. // Voprosy Atomnoy Nauki i Tekhniki. Seriya: Yaderno-   reaktornye konstanty. Vypusk 2, (1999).
3. L.Z.Dzhilavyan, et al., Phys. Part. Nucl. 50, 626 (2019).
4. L.Z.Dzhilavyan, et al., Bull. Russ. Acad. Sci. Phys. 84, 356 (2020).
5. L.Z.Dzhilavyan, et al., Phys. Atom. Nucl. 84, (2021).
6. G.Nedorezov, et al., Bull. Russ. Acad. Sci. Phys. 83, 1161 (2019).