Development of a compact HAPG crystal Von Hamos X-ray spectrometer forextended and diffused sources

Abstract

Bragg spectroscopy is one of the best established experimental methods for high energy resolution X-ray measurements; however, this technique is limited to the measurement of photons producedfrom well collimated (tens of microns) or point-like sources and becomes quite inefficient for photonscoming from extended and diffused sources. The possibility to perform simultaneous measurementsof several energies is strongly demanded when low rate signals are expected and single angular scansrequire long exposure times. A prototype of a high resolution and high precision X-ray spectrometerworking also with extended isotropic sources, has been developed by the VOXES collaboration atINFN Laboratories of Frascati, using Highly Annealed Pyrolitic Graphite (HAPG) crystals in a semi- Von Hamos configuration, in which the position detector is rotated with respect to thestandard Von Hamos one, to increase the dynamic energy range. The aim is to deliver a cost effectivesystem having an energy resolution at the level of eV for X-ray energies from about 2 keV up to tensof keV, able to perform sub-eV precision measurements with non point-like sources. The proposedspectrometer has possible applications in several fields, going from fundamental physics to quantummechanics tests, synchrotron radiation and X-FEL applications, astronomy, medicine and industry.In particular, this technique is fundamental for a series of nuclear physics measurements like, forexample, the energies of the exotic atoms radiative transitions which allow to extract fundamentalparameters in the low energy QCD in the strangeness sector. In this work, the working principleof the spectrometer is presented, together with the tests and the results, in terms of resolution andsource, size obtained for Fe(K\alpha1,2), Cu(K\alpha1,2), Ni(K\beta), Zn(K\alpha1,2), Mo(K\alpha1,2) and Nb(K\beta)lines.