# First results on measurements of spectrum and angular distribution of transition radiation using a silicon pixel sensor on a TimePix3 chip

Schioppa E.J., Dachs F., Alozy J., Belyaev N., Campbell M., Cherry M., Doronin S., Filippov K., Fusco P., Gargano F., Heijne E., Konovalov S., Krasnopevtsev D., Llopart X., Loparco F., Mascagna V., Mazziotta N., Pernegger H., Ponomarenko D., Prest M., Rembser C., Romaniouk A., Savchenko A., Schaefer D., Sergeeva D., Shulga E., Smirnov S., Smirnov Y., Soldani M., Spinelli P., Strikhanov M., Tischenko A., Teterin P., Tikhomirov V., Vallazza E., Van Beuzekom M., Vorobev K., Zhukov K.,

Comunicazione
I - Fisica nucleare e subnucleare
Aula 32B-1 - Mercoledì 19 h 11:00 - 13:00
X-ray Transition Radiation detectors (TRD) are used for particle identification in both high energy physics and astroparticle physics. Particle identification is usually achieved with a threshold effect of the TR at particle gamma factors below $\sim$ 500. However, many experiments require particle identification up to gamma $\sim 10^{5}$, which is difficult to achieve with current detectors, based on the measurement of the photon energy together with particle ionization losses. More information on the Lorentz factor is carried by the angular distribution. TRD based on pixel detectors give a unique opportunity for precise measurements of spectral and angular distributions of TR at the same time. A 500 $\mu$m thick silicon sensor bump bonded to a Timepix3 chip was used in a test beam measurement at the CERN SPS. A beam telescope was employed to separate beam particle clusters from the potential TR clusters. Spectral and angular distributions of transition radiation were studied with high precision for the first time using beams of pions, electrons and muons at different energies. In this talk, the measurement and analysis techniques are described, and the first results are discussed.