⁶Li Embedded Biaxially Stretched Scintillation Films for Thermal Neutron Detection and Neutron/Gamma Discrimination

Abstract

Biaxially stretched composite polyethylene naphthalate (PEN) films (BSCPF) embedded with submicron lithium fluoride ( 6 LiF) particles and luminescent molecules were fabricated to make large area scintillation films (%1 m  1 m) for thermal neutron detection. BSCPF had 20.2% higher neutron light yield as compared to unstretched composite film (UCPF), and were 2.46 AE 1.47 times more efficient for detecting thermal neutrons than lithiated glass GS20 above lower level discriminator corresponding to an intrinsic efficiency for gamma <10 À6 . MCNPX simulations for a layered BSCPF detector resulted 6.1 cps for 1 ng 252 Cf, thus meeting the Pacific Northwest National Laboratory criteria for absolute neutron detection efficiency and intrinsic gamma-neutron discrimination. BSCPF have alpha to beta ratio of 0.25, which is higher than that for UCPF (0.11), and also for GS20 (0.22), which offers the possibility of excellent neutron/gamma discrimination.

Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

“…In a recent extension of this work poly(2-vinylnaphthalene) is replaced by biaxially stretched poly(ethylene naphthalate) (PEN) films [12]. Stretched polymers have an increased crystallinity leading to a better energy transport.…”

A model survey meter using undoped poly (ether sulfone)

“…Modern refining techniques have made it possible for undoped aromatic ring polymers to be used as scintillation materials [7,8]. Examples include polycarbonates and poly (ethylene terephthalate) [2,[9][10][11][12][13][14][15][16][17][18][19][20][21]. Moreover, optical characteristics of high-purity polystyrene and poly (vinyltoluene) have been subsequently re-examined [22,23].…”

Polysulfone as a scintillation material without doped fluorescent molecules

“…The optical characteristics of their base substrates have been significantly improved by advanced refining techniques, and a previously unknown fluorescence mechanism in these scintillation materials was revealed [4][5][6][7]. In addition, aromatic ring polymers no longer need doped fluorescent guest molecules to detect radiation [8][9][10][11][12][13]. Useful aromatic ring polymers include poly (ethylene naphthalate), which has a 420-nm emission maximum and is used in radiation survey metres as an effective alternative for more common scintillation materials [14,15].…”