Assembling and testing of ATLAS micro-strip semiconductor detectors

In the summer of 2020, ATLAS Inner Tracker (ITK) strip module semiconductor detectors will be assembled and tested. As part of the pre-production phase of the ITK construction, establishing reception tests of electronic circuits and Silicon sensors will be setup, as well as electric characterisation and thermal cycling stations for fully assembled detectors. The student will be involved in all steps of the assembly and testing processes, helping to prepare the group for site qualification in late 2020.

Project type: Detector development & testing

Prerequisites: None

Preferred dates: Mid-July to August

Main SupervisorAndy Blue

Second SupervisorCraig Buttar

Top challenges to new physics

One of the main challenges of the Large Hadron Collider (LHC), and of the experiments located on its 27km ring, is to move the edge of our knowledge of particle physics and search for evidence of physics beyond the standard model.‌

The energy reached by the LHC and the extraordinary amount of data collected, allow the search for new heavy particles that could reveal their presence in the observation of any unforeseen signal (peak) or in a subtle deviation of the measurements from the expectations, depending on the probability of the creation of the new particle and its mass.

The perfect area where to search for new heavy particles is the top-antitop quark production, since it is likely that the new “resonances” will couple strongly with the heaviest particles existing in the standard model.

Among all the mechanisms to produce a top-antitop pair, the associated production with a Z boson is still relatively unexplored, since the first measurements of this process have just been recently published by ATLAS and CMS. The aim of this project is to explore the usage of ttZ production measurements in the search for new physics. We will also investigate which improvements can be made to future analyses to increase the sensitivity to the kinematic regions where new physics is more likely to be..

Project type: Data Analysis

Prerequisites: Some knowledge of C++ and Python

Preferred dates: June / July / early August

Main SupervisorFederica Fabbri

Second SupervisorMark Owen

Study of the Higgs boson decay into pairs of b-quarks with the ATLAS detector

The Standard Model of the elementary particles physics is an established theory which provides a fundamental description of all elementary particles and their interactions. A key ingredient of the Standard Model is the Higgs boson, whose existence has been postulated in the early sixties and experimentally proved at the Large Hadron Collider in 2012. It can be produced via various processes and it can decay to several final states. The dominant decay of the SM Higgs boson is into pairs of b-quarks, with an expected probability of 58 %. However, the large hadron activity makes the search for the H → bb decay very challenging. To be able to discriminate the signal from the backgrounds, the associated production process of the Higgs boson with the W or Z bosons (VH), is used to trigger on a cleaner signature in the detector, therefore reducing the backgrounds. In this project, we will study the Higgs boson decaying into pairs of b-quarks in the VH production mode with data from the ATLAS collaboration at the LHC, using a new detection technique.

Project type: Simulation and Data Analysis

Prerequisites: Linux and good scientific programming experience in Python/C++

Preferred dates: June - July

Main SupervisorGiuseppe Callea

Second SupervisorAidan Robson

Neutrino interactions in the T2K near detector

T2K is a long baseline neutrino experiment in Japan studying neutrino oscillation, the phenomena by which neutrinos created in one flavour state are measured some time later in another flavour state. The rate of matter oscillation vs antimatter oscillation is determined by a phase term called delta CP and in the future T2K will measure this complex phase. Such a measurement may give us information about the formation of matter in the early universe including the observed baryon asymmetry. A critical part of this effort will be measuring neutrino interactions in matter and understanding the underlying physics of these interactions. Such interactions have recently become the focus of considerable attention as our understanding of these interactions will ultimately determine the precision of our experiment. A significant research effort is required to develop the theoretical models to the level needed to extract useful physics such as delta CP. T2K has the largest dataset of neutrino target interactions in the world and the most comprehensive program of measurements of this type but much work remains to be done. This project will involve analysing real and simulated data from a new near detector WAGASCI which has unique capabilities in measuring neutrino interactions. This project will involve code development in C++ and python and any prior experience in these languages or similar is an advantage.

Project type: Data analysis & detector simulation

Prerequisites: Preferably some programming experience, particularly with C++ and python.

Preferred dates: Any

Main SupervisorJohn Nugent

Second SupervisorPhill Litchfield

Matter-anti-matter asymmetries at the LHCb experiment

The LHCb experiment at the Large Hadron Collider (LHC), CERN, is designed specifically to make high precision measurements of decays of hadrons containing charm and beauty quarks. These are compared to the theoretical predictions of the Standard Model (SM) in order to look for discrepancies which may indicate new physics effects. Measurement of the lifetimes of charmed hadrons are challenging, both theoretically and experimentally, but with sufficient precision may reveal new physics. Should a discrepancy between theory and experiment be found this could indicate interference from non-SM particles, which can enhance or suppress the decay of charmed hadrons. LHCb has recorded the largest datasets of decays of charmed hadrons in the world. Combined with its high precision tracking system this makes it an ideal place to perform such tests of the SM.

Using both real and simulated data from LHCb, the student will work towards a measurement of the decay time dependent matter-anti-matter asymmetry of neutral charmed mesons. This will require extensive use of the ROOT data analysis software package in order to parametrise signal and background, account for detector resolution and efficiency effects, and extract the lifetime of the signal decays.

Project type: Data analysis

Prerequisites: Some programming experience, particularly with Linux shell scripting, C++ and Python. Prior experience with ROOT would be beneficial, but not essential.

Preferred dates: Mid-June to August

Main SupervisorMichael Alexander

Second SupervisorLars Eklund

A proton-proton collision recorded by LHCb from May 2017