Alignment of L3 subshell vacancy states in Au, Bi, Th and U following photoionisation and effect of external magnetic field

Muhanad Alrakabi; Sanjeev Kumar; Veena Sharma; Gurjeet Singh; Devineder Mehta

doi:10.1140/epjd/e2013-30356-7

2020 Impact factor 1.425

Atomic, Molecular, Optical and Plasma Physics

Eur. Phys. J. D (2013) 67: 99
https://doi.org/10.1140/epjd/e2013-30356-7

Regular Article

Alignment of L₃ subshell vacancy states in Au, Bi, Th and U following photoionisation and effect of external magnetic field

Muhanad Alrakabi¹^,2, Sanjeev Kumar¹^,3^a, Veena Sharma¹, Gurjeet Singh¹ and Devineder Mehta¹

¹ Department of Physics, Panjab University, 160 014 Chandigarh, India
² Department of Physics, College of Science, Al-Mustansirya University, 47162 Baghdad, Iraq
³ Department of Applied Sciences, Chitkara University, 140 401 Rajpura, India

^a e-mail: sanjeevkchandel@gmail.com

Received: 7 June 2012
Received in final form: 8 February 2013
Published online: 7 May 2013

Abstract

Alignment of the L₃ (J = 3 / 2) subshell vacancy states in the Au, Bi, Th and U elements following photoinisation have been investigated through angular distribution measurements of subsequently emitted L₃ subshell X-rays. The 59.54 keV unpolarised γ-rays from the ²⁴¹Am radioactive point-source were used to ionize the target and the subsequently emitted L X-rays were measured using an HPGe detector. The improved experimental procedure along with correct evaluation scheme permits straight-forward method for investigating anisotropy in photo-excited L X-ray emission. The efficiency of the detector and the absorption correction for the emitted L X-rays in the target remain fairly constant as the target-detector assemblage remains undisturbed in the present measurements at various angles. Isotropically emitted L₁ subshell (J = 1 / 2) X-rays measured simultaneously were used to normalize the L X-ray spectra taken at different emission angles. The present measurements clearly support small theoretical predicted values of the alignment parameter; however, it is difficult to infer regarding the predicted anisotropic trends. The angular distribution measurements for the L₃ subshell X-ray emission were also performed by placing the target in magnetic field ∼ 0.6 T. The earlier reported large anisotropy in angular distribution of the emitted L₃ subshell X-rays and significant effect of external magnetic field on the angular distribution are ruled out.