Background elimination using the SNIP method for Bragg reflections from a protein crystal measured by a time-of-flight single-crystal neutron diffractometer

Not scheduled
15m
OIST

OIST

1919-1 Tancha, Onna-son, Kunigami-gun Okinawa, Japan 904-0495
poster presentation Track2: Offline software

Speaker

Katsuaki Tomoyori (Japan Atomic Energy Agency)

Description

In neutron protein crystallography, it should be also emphasized that the weak Bragg reflections due to the large unit cells may be buried beneath the strong background caused by the incoherent scattering of hydrogen atoms. Therefore, the background estimation from the source is more reliable to improve the accuracy of Bragg integral intensity. We propose the adoption of Statistics-sensitive Nonlinear Iterative Peak-clipping (SNIP) algorithm for background estimation [1], which can eliminate the background from the source spectrum as well as statistically enhance low peaks. In addition, it was recently reported that the Landau and Vavilov distributions, which are used to describe the energy loss of charged particles traversing a thin absorber were found to be in excellent agreement with the observed TOF profile [2]. I show that it may be beneficial to establish a profile-fitting method with the combined use of the Landau/Vavilov functions to faithfully reproduce the TOF peak shape and a SNIP background evaluation algorithm to eliminate statistical fluctuations. [1] Ryan CG et al (1988) Nucl. Instr. Meth. Phys. Res. Sect. B 34:396-402 [2] Tomoyori K et al (2013) Nucl. Instr. Meth. Phys. Res. Sect. A 723:128-135

Primary author

Katsuaki Tomoyori (Japan Atomic Energy Agency)

Co-authors

Dr Kazuo Kurihara (Japan Atomic Energy Agency) Dr Taro Tamada (Japan Atomic Energy Agency)

Presentation Materials