Cherenkov Diffraction Radiation Emissions from Single Electrons and Positrons on a Fused Silica Radiator

Beam diagnostics are crucial for smooth accelerator operations. Many techniques rely on instrumentation in which the beam properties are significantly affected by the measurement. Novel approaches aim to use Cherenkov Diffraction Radiation (ChDR) for non-invasive diagnostics. Unlike regular Cherenkov Radiation, the charged particles do not have to move inside of the medium, but it is sufficient for them to move in its vicinity as long as they are faster than the speed of light in the medium. Changes to the beam properties due to ChDR measurements are consequently negligible. To examine ChDR emission under different conditions, we placed a fused silica radiator in the DESY II Test Beam. We observed a linear increase in ChDR intensity for electron and positron momenta between 1 GeV/c and 5 GeV/c. Additionally, we found that electrons produce significantly more ChDR than positrons for increasing particle momenta. The results suggest a need for further research into the ChDR generation by electrons and positrons and may find application in the design of future beam diagnostic devices

Search for Direct Stau Pair Production at 8 TeV with the CMS Detector

In the Standard Model (SM) of Particle Physics, the particle masses are generated through theHiggs mechanism through the breaking of the electroweak symmetry. The Higgs mechanismpredicts the existance of the Higgs boson. Recent results from both the ATLAS and CMS experiments report the discovery of a new particle consistent with the Higgs boson. However, theHiggs sector of the SM suffers from the so-called hierarchy problem to which Supersymmetryis a possible solution. Supersymmetry postulates the existence of new particles, partners to theknown particles, with spin differing by half a unit. The search for these new particles is, in thisway, an important endeavour in the search for a deeper understanding of the fundamental theoryof elementary particles.This thesis describes a search for the supersymmetric partner of the tau lepton (stau). Thestaus subsequently decay to a regular tau lepton and a neutralino. The thesis considers the semihadronic final state, where one of the taus decay to an electron or muon and the other decayshadronically. The challenge in this analysis rests with the identification of the tau lepton, wherethe fake tau background from W+Jets events proved of particular importance.Results from CMS proton-proton data recorded in 2012 at 8 TeV are presented, with anintegrated luminosity of 19.7 −1 . The events were required to have an opposite sign pair ofan electron or muon and a tau in association with missing transverse energy and no b-jets. Themain background, fake taus, was measured from data. The analysis employs a simplified modelspectra simulation to generate the signal simulation, allowing the final result to be presentedin an as model independent way as possible. No significant evidence of signal was observedand limits were established on the cross section times branching ratio. The results were alsointerpreted under the MSSM scenario where the stau is the NLSP and the neutralino the LSP

Beamline for Schools: beam and detectors 2021

This document describes the DESY II test beam facility available for the winning teams of the Beamline for Schools competition in 2021, and lists the detectors that the participants can use to build their experiments

Beamline for Schools: experiment examples 2021

This document lists a series of experiments that can be performed at the DESY II test beam facility in the context of the Beamline for Schools competition 2021. The high-school students who take part in the competition can use this document as a reference to develop their proposals

The EXTRA-BL4S experiment for the measurement of the energy and angular distributions of transition radiation X-rays

We have designed and implemented an experiment to measure the angular distributions and the energy spectra of the transition radiation X-rays emitted by fast electrons and positrons crossing different radiators. Our experiment was selected among the proposals of the 2021 Beamline for Schools contest, a competition for high-school students organized every year by CERN, and was performed at the DESY II Test Beam facility area TB21, using a high-purity beam of electrons or positrons with momenta in the range from $1$ to $6 ~GeV/c$. The measurements were performed using a $100~\mu m$ thick silicon pixel detector, with a pitch of $55~\mu m$. Our results are consistent with the expectations from the theoretical models describing the production of transition radiation in multilayer regular radiators