X-ray production by 500 MeV electron beam in a periodically structured monocrystalline target of GaAs V.V. Kaplin a , S.I. Kuznetsov b , N.A. Timchenko a , S.R. Uglov a , V.N. Zabaev a, * a Nuclear Physics Institute, Tomsk Polytechnic University, Lenin Ave. 2-a, P.O. Box 25, 634050 Tomsk, Russia b Tomsk Polytechnic University, Lenin Ave. 30, Tomsk, Russia Received 7 December 1999; received in revised form 5 April 2000 Abstract The experiment at the Tomsk synchrotron on generation of 27 keV X-rays by 500 MeV electrons in a new type of a periodical crystalline target is presented. The target has been made on the surface of a GaAs crystal plate by means of microlithography. The etched microstructure is a system of about 300 strips, 14 lm thick, 100 lm high and the gaps between the strips are 29 lm. The measured spectra and orientational dependences of the X-rays emitted at a Bragg angle are discussed. The generated radiation consists of parametric X-ray radiation (PXR) and diracted X-ray transition radiation (DTR). It is shown that the intensity of the DTR component of generated X-rays is much higher than that of the PXR. Ó 2001 Elsevier Science B.V. All rights reserved. Keywords: Coherent radiation; Transition X-ray; Relativistic electrons; Crystal 1. Introduction This work is a continuation of the investiga- tions of X-ray production in a new type of a pe- riodical crystalline structure [1,2]. It is more complicated than a single crystal or a simple stack consisting of amorphous foils. The multistructured target was created for developing the recently proposed new concept of coherent X-ray produc- tion in compound ``multifoil + crystal'' [3,4] and periodical multicrystal [5] targets. According to this concept, eective X-ray sources on such basis combine two well-known methods of X-ray production from periodical structures: resonance X-ray transition radiation (RTR) and parametric X-ray radiation (PXR). This makes it possible to use the best features of both types of X-ray emis- sion: high intensity of RTR and monochromaticity of PXR. We used a new type of target that was etched on the surface of a GaAs plate, as a ¯at periodical multistrip structure by a plasma chem- ical method. It is a system of about 300 strips, 14 lm thick, 100 lm high and the gaps between the strips are 29 lm. Its substrate is about 5 lm thick. The cross-section of the target is shown schemat- ically in Fig. 1. When the electrons are crossing a Nuclear Instruments and Methods in Physics Research B 173 (2001) 238±240 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +7-3822-417-939; fax: +7- 3822-423-934. E-mail address: zabaev@npi.tpu.ru (V.N. Zabaev). 0168-583X/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 0 0 ) 0 0 1 8 6 - 5