Focusing properties of mosaic crystals

X-ray instruments with mosaic crystals are proposed and used in many applications in synchrotron radiation, medical physics and astrophysics. These crystals present a parafocusing of the x-ray beam in the diffraction plane, which is thoroughly analyzed in this paper. We studied the evolution of the cross- section of the diffracted beam, using several samples of Highly Oriented Pyrolythic Graphite crystals coming from different suppliers. The experiment has been performed at the European Synchrotron Radiation Facility (beamline BM5). The results clearly show a parafocusing effect in the 1:1 magnification ratio along the diffraction plane and a defocusing effect along the perpendicular plane. The secondary extinction coefficient is also measured.

[1]  李幼升,et al.  Ph , 1989 .

[2]  Andreas K. Freund,et al.  Direct observation of mosaic blocks in highly oriented pyrolytic graphite , 1997 .

[3]  Andreas K. Freund.  Applications of mosaic crystals to high-brilliance x-ray optics , 1993, Optics & Photonics.

[4]  Giovanni Pareschi,et al.  Polarimetric performance of a Bragg hard x-ray (>10 keV) concentrator , 1994, Optics & Photonics.

[5]  A. Del Guerra,et al.  Small-field imaging properties of narrow energy band X-ray beams for mammography , 1995, 1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record.

[6]  Giovanni Pareschi,et al.  Comparative study of hard x-ray (>10 keV) focusing techniques for space astronomy , 1995, Optics & Photonics.

[7]  Francesco Cerrina,et al.  A conceptual model for ray tracing calculations with mosaic crystals , 1992 .

[8]  Andreas K. Freund,et al.  Mosaic crystal monochromators for synchrotron radiation instrumentation , 1988 .

[9]  Filippo Frontera,et al.  Narrow energy band X-rays via mosaic crystal for mammography application , 1995 .

[10]  Angelo Taibi,et al.  Quasi-monochromatic x-ray source for mammography via crystal array , 1997, Medical Imaging.

[11]  M Gambaccini,et al.  MTF evaluation of a phosphor-coated CCD for x-ray imaging. , 1996, Physics in medicine and biology.

[12]  Sean Brennan,et al.  X-ray diffraction properties of highly oriented pyrolytic graphite , 1996, Optics & Photonics.

[13]  G. E. Bacon,et al.  Secondary extinction and neutron crystallography , 1948 .

[14]  Andreas K. Freund,et al.  A tunable filter for reducing higher order contamination of monochromatic neutron beams , 1985 .

[15]  G. Pareschi,et al.  Hard X-ray imaging via focusing optics with mosaic crystals , 1995 .

[16]  Gene E. Ice,et al.  Mosaic crystal X-ray spectrometer to resolve inelastic background from anomalous scattering experiments , 1990 .

[17]  Angelo Taibi,et al.  Evaluation of a digital X-ray detector based on a phosphor-coated CCD for mammography , 1997 .

[18]  W. McCulloch.  Of I and It , 2015 .