Bachelor student Projects

Projects for bachelor students in the Nikhef ATLAS group

date: January 2015

This is an overview with all available bachelor student projects in the Nikhef ATLAS group.

If you have your own research proposal, need more detailed information on the (availability) of individual proposals or would like to discuss about other available projects in the group you are always welcome to contact either the contact person for the project and/or the Nikhef ATLAS group leaders:

Wouter Verkerke [ E-mail: verkerke_at_nikhef.nl, Tel 020-5925134, Nikhef room H250]

Paul de Jong [ E-mail: h26_at_nikhef.nl, Tel 020-5922087, Nikhef room H253]

1) Event generator voor Higgs bosonen bij de LHC

Supervisors: Ivo van Vulpen (UvA staff), unknown (PhD student)

Research description: Bij de Large Hadron Collider op CERN worden protonen met hoge snelheid op elkaar geschoten. In die botsingen worden nieuwe deeltjes gemaakt en sinds 2 jaar weten we ook dat er soms Higgs bosonen gemaakt worden. Deze deeltjes leven erg kort en vallen uit elkaar in bekende deeltjes die wel lang genoeg leven om ze te zien in onze apparatuur. Het is aan ons de taak om uit de dingen die we gezien hebben in onze detectoren te vertalen naar de eigenschappen van het Higgs boson. Om die vertaalslag te kunnen maken en de Higgs bosonen te onderscheiden van 'gewone' botsingen moeten we simuleren hoe ze eruit zien.

Doel van dit project is om een eigen event-generetor op te zetten in Python. We 'maken' een Higgs boson met bepaalde eigenschappen en laten die vervolgens (getrapt) uit elkaar vallen. Dat gaat volgens kansverdelingen. Uiteindelijk kunnen we dan de signalen in de detector bekijken als functie van de eigenschappen van het Higgs boson die we er zelf in kunnen stoppen. Wat gebeurt er bijvoorbeeld als de LHC versneller over 2 maanden weer aangaat op een energie die 2x zo hoog is ? Als het project het toelaat kunnen we deze tool ook gebruiken om de 'gewone' botsingen te onderscheiden van die van een Higgs boson.

Dit project laat je kennismaken met de natuurkunde van deeltjesfysica, het simuleren van natuurkundige processen, numerieke technieken en data-analyse.

2) Dark Matter at the LHC: Search for invisible Higgs bosons

Supervisors: David Berge (UvA staff), David Salek (PostDoc) and Gabriele Sabato (PhD student)

Research description:

The matter in the Universe is dominated by an up to now unknown component called Dark Matter. The nature of this Dark Matter is one of the major open question in modern astro particle physics. In the last decades a lot of efforts were put into the search for Dark Matter particles, and experiments at the Large Hadron Collider (LHC) form part of this search effort. In ATLAS for example, new particles that could make up Dark Matter are searched for in the mass range of GeV to several TeV. One fascinating possibility of producing Dark Matter and discovering it at the LHC is via the coupling to the Higgs boson, which was itself only discovered in 2012. The student's task will be to implement an analysis code to reconstruct events where a Z boson and a Higgs boson are produced together. In order to do that he/she will learn how to use the ROOT software package and will then be asked to study simulated ATLAS data. Finally he/she will try to improve the baseline analysis improving the rejection of the background over the signal.

Schedule

week 1: Introduction to theory and ATLAS experiment

week 2: Introduction to ROOT

week 3/5: Implementation of ZH event selection with simulated background and signal sample.

week 6/9: Optimization of the baseline analysis in order to improve the significance.

week 10: Presentation of the results

week 11/12: Writing and discussion

3) Triple Higgs diagram

Supervisors: Bob van Eijk (staff) and Tim Wolf (PhD student)

Research description: Met de ontdekking van het Higgs deeltje, waar de massa is bepaald, voorspelt het minimale Standaard Model de overige eigenschappen van het Higgs deeltje. Een van de voorspellingen (die de vorm van de Higgs potentiaal vastleggen) is sterkte van het triple Higgs diagram. In de praktijk betekent dit dat een voorspelling wordt gemaakt voor de werkzame doorsnede waarbij twee Higgs deeltjes tegelijkertijd worden geproduceerd.

Tijdens dit project zullen we botsingen van de LHC analyseren met twee Higgs deeltjes in de eindtoestand. We zullen simulaties van botsingen genereren en bepalen of we dit signaal met de toekomstige data van ATLAS kunnen isoleren van de achtergrond.

4) Hisparc data acquisition

Supervisors: Bob van Eijk (staff) and Arne de Laat (PhD student)

Research description: HiSPARC (http://www.hisparc.nl/) is a network that consists of more than 100 cosmic ray detection stations in NL, UK and DK. Aim is to measure direction and energy of (very) high energy cosmic particles. Stations are operated by scientists and high-school students. Each detection stations submits data to Nikhef via internet. Monitoring and remote control runs over a VPN/VNC.

Project: An event generator needs to be designed that generates 'real' data. Secondly a number of real time data analysis/data selection procedures need to be developed to optimise data acquisition.

Tools: Test station at Nikhef and a database containing more than 8 years of data

Programming language: C.

5) Searching for supersymmetry at the LHC

Supervisors: Paul de Jong (UvA staff) and Ingrid Deigaard (PhD student)

Research description: At the Large Hadron Collider (LHC) at CERN protons are collided to investigate the smallest constituents of the Universe, the elementary particles. The current model of particle physics, The Standard Model, is being tested and possible extensions are investigated. One of these extensions is Super Symmetry.

With the increase in collision energy from 8 TeV to 13 TeV, the cross sections for possible supersymmetric production will increase significantly. Especially the cross section for strongly produced supersymmetry (squarks and gluinos) will increase by a factor 30-100.

For some supersymmetric models, squarks can decay into a final state containing a higgs boson. In this project, we will study the sensitivity for such decays in events with many jets, missing transverse energy, and no leptons.

6) Scalar top quarks

Supervisors: Paul de Jong (UvA staff) and Pierfrancesco Butti (PhD student)

Research description: Scalar (i.e. spinless) top quarks are predicted by supersymmetric extensions of the Standard Model. These scalar top quarks could decay into tau leptons which can be detected with ATLAS in Run 2 of the LHC. This project comprises a study of the expected significance of two variants of this analysis, the lepton-hadron and hadron-hadron channels, in Run 2. The goal is to improve the Run 1 analysis, and determine at what luminosity we are more sensitive to scalar top quarks than the current limits.

In this project, the students will learn about the theory of supersymmetry and scalar top quarks, and carry out an analysis of ATLAS data or simulated data with the ATLAS data analysis tools.

7) Simulations / Quality tests for the ATLAS High-Luminosity LHC Upgrade

Supervisors: Peter Vankov (postdoc)

Research description: One of the key sub-systems of the ATLAS experiment at the Large Hadron Collider (LHC) is the Inner Detector (ID), designed to provide excellent charged particles momentum and vertex resolution measurements.

At Phase-2 of the LHC run the operating luminosity of the collider will be increased significantly. This will imply an upgrade of all ATLAS subsystems. In particular, the ID will be fully replaced with a tracker completely made of Silicon, having higher granularity and radiation hardness. The R&D process for the new ATLAS ID is now ongoing. Different geometrical layouts are simulated and their performance is studied under different operating conditions in search for the optimal detector architecture. Also, the performance of the new Si-sensors/modules is under investigation with dedicated laboratory tests.

The focus of the project could be on the simulation of the High-Luminosity LHC version of the ATLAS Inner Detector. The student will learn how a high-energy physics experiment is designed and optimized. Alternatively, if possible at that moment, the student could work on a project at the Nikhef Silicon laboratory at the test-bench for new ATLAS Si-strip detectors and participate in the quality assurance procedure for the new ATLAS Si detectors.