Chiara La Licata

Radiation Monitoring with Diamond Sensors for the Belle-II Vertex Detector

The Belle II detector is currently under construction at the SuperKEKB electron-positron high-luminosity collider, that will provide an instantaneous luminosity 40 times higher than that of KEKB. There- fore the Belle-II VerteX Detector (VXD) will operate in a very harsh environment. A radiation monitoring and beam abort system is needed to safely operate the VXD detector in these conditions. This system is based on 20 single crystal CVD diamond sensors placed in 20 key positions in the vicinity of the VXD and interaction region. In this contribution we describe the system design and we present the procedures followed for the characterisation and calibration of the diamond sensors. We discuss also the performance of the prototype system during the first SuperKEKB commissioning phase in February-June 2016.

Measurements of the Y(1S), Y(2S), and Y(3S) differential cross sections in pp collisions at sqrt(s) = 7 TeV

Differential cross sections as a function of transverse momentum pT are presented for the production of Υ(nS) (n = 1, 2, 3) states decaying into a pair of muons. Data corresponding to an integrated luminosity of 4.9 fb−1 in pp collisions at √ s = 7 TeV were collected with the CMS detector at the LHC. The analysis selects events with dimuon rapidity |y| < 1.2 and dimuon transverse momentum in the range 10 < pT < 100 GeV. The measurements show a transition from an exponential to a powerlaw behavior at pT ≈ 20 GeV for the three Υ states. Above that transition, the Υ(3S) spectrum is significantly harder than that of the Υ(1S) and Υ(2S). The ratios of the Υ(3S) and Υ(2S) differential cross sections to the Υ(1S) cross section show a rise as pT increases at low pT, then become flatter at higher pT. Submitted to Physics Letters B c