 | INFN - Laboratori Nazionali di Frascati, Italy |  | October 20-29, 2015 |
DAFNE-Light is the INFN-LNF Synchrotron Radiation Facility that uses the electron storage ring of the DAFNE accelerator as radiation source. In the DAFNE-Light facility there are five beam lines. DAFNE-Light is a material science facility and a test facility, where new detectors and optics can be tested in a wide energy range from IR to soft X-rays.
The structure of the laboratories that will be organized is as follow:
Infrared detectors for chemical imaging and beam diagnostics (M. Cestelli Guidi, A. Drago)
Synchrotron radiation in the infrared (IR) range is widely used as a bright light source for material characterization, from solid state physics to chemistry, biology and cultural heritage science. The extraction of IR radiation from the DAFNE front end, the beam line optics and the FT-IR interferometer will be presented and discussed. Students will take part in an imaging experiment on a biological tissue using an IR microscope coupled with a multichannel IR imaging detector.
In the second part of the laboratory session, some solid state detectors, based on HgCdTe technology, will be presented. These devices are able to produce pulsed electrical signals proportional to the infrared light emitted as synchrotron radiation by the bunch pattern stored in DAFNE electron ring. The detectors, both single pixel and multi-pixel, can be used as beam diagnostics tool being able to resolve in time the infrared time emission. Students will measure the pulsed time structure of the DAFNE electron beam.
Diamond Radiation Detectors: Principles and applications (E. Pace)
Diamond is an extraordinary material as radiation-sensitive substrate for high-energy photon (UV, X-rays, gamma rays) and particle detection.
It is currently a unique candidate for harsh environments as space and/or for ultra-fast photon or particle detection with time resolution better than a few hundreds of picoseconds. This is why diamond detectors are replacing silicon detectors in many synchrotron, space or particle experiments.
An interactive lecture in laboratory will describe the properties of diamond detectors, how to fabricate diamond-based devices and some of the main applications as X-UV photon detectors, particle detectors and dosimeters.
In some details, single pixel detectors as well as pixel array and how they operates as UV photo-resistor will be shown; applications as ultra-fast detector for pulsed radiation and time resolving experiments will be also discussed. Also the application of diamond devices as effective radiation dosimeters in medical or space experiments will be discussed.
With the availability of synchrotron radiation sources, X-ray absorption spectroscopy (XAS) developed into a widely used and powerful tool for the study of materials with applications in chemistry, physics, biology and other fields by identifying their local atomic structure.
This technique is closely related to photoelectron spectroscopy, Auger electron spectroscopy, and X-ray fluorescence spectroscopy, can be used to study the chemical environment of an atomic element in an unknown material and can be applied to crystalline, nanostructured or amorphous materials, liquids and molecular gases.
X-ray absorption spectroscopy principles, applications and technique will be presented and students will perform measurements using ionization chambers in transmission mode and silicon drift detectors in fluorescence mode.
XPS and Raman Spectroscopy applied to surface science (R. Larciprete, A. Di Gaspare)
A surface science experiment gives the possibility to monitor the adsorption of reactive gases on metal surfaces. Using X-ray photons of 1486.6 or 1253.6 eV, as excitation source, it is possible to study the photoemission of electrons from a sample. The kinetic energy of the excited electrons can be measured using a spherical analyzer with channeltron detectors and the resulting X-ray Photoelectron Spectrum (XPS) will allow the identification of the nature and of the chemical state of the atoms residing in the near surface layers of the sample.
The principle of XPS will be exposed to the students who will measure spectra of a metal sample before and after the exposure to the flux of a reactive gas (i.e. O2) to follow the modification of the surface composition. In order to monitor the gas delivery, a quadrupole mass spectrometer will be used to provide the composition of the residual gas in the vacuum chamber by revealing the fragmentation pattern induced by electron bombardment.
In the second part of the laboratory session Raman microscopy will be used to detect monolayer graphene flakes on SiO2 achieved exfoliating graphite. A focused laser beam at 532 nm will be used as excitation source and a CCD as detector to measure the Raman spectrum. By scanning the sample under the laser beam the entire map will be produced providing the visualization of the graphene flakes.
