Master Projects

Master Thesis Research Projects

The following Master thesis research projects are offered at Nikhef. If you are interested in one of these projects, please contact the coordinator listed with the project.

[MORE PROJECTS TO COME!]

Last year's MSc Projects

The XENON Dark Matter Experiment: Data Analysis

The XENON collaboration is currently commissioning the XENON1T detector, soon to be the world’s most sensitive direct detection dark matter experiment, with the Nikhef group playing an important role in this work. The detector operates at the Gran Sasso underground laboratory and consists of a so-called dual-phase xenon time-projection chamber filled with 3500kg of ultra-pure xenon. Our group has an opening for a motivated MSc student to do data-analysis on this new detector. The work will consist of understanding the signals that come out of the detector and in particular focus on the so-called double scatter events. We are interested in developing methods in order to interpret the response of the detector better and are developing sophisticated statistical tools to do this. This work will include looking at data and developing new algorithms in our Python-based analysis tool.

Contact: Patrick Decowski

XAMS Dark Matter R&D Setup

The Amsterdam Dark Matter group has built an R&D xenon detector at Nikhef. The detector is a dual-phase xenon time-projection chamber and contains about 4kg of ultra-pure liquid xenon. We plan to use this detector for the development of new detection techniques (such as utilizing new photosensors) and to improve the understanding of the response of liquid xenon to various forms of radiation. The results could be directly used in the XENON experiment, the world’s most sensitive direct detection dark matter experiment at the Gran Sasso underground laboratory. We have several interesting projects for this facility. We are looking for someone who is interested in working in a laboratory on high-tech equipment, modifying the detector, taking data and analyzing the data him/herself. You will "own" this experiment.

Contact: Patrick Decowski

ATLAS : Beyond Standard Model with multiple leptons

The Standard Model of particle physics (SM) is extremely successful, but would it hold against of check of with data containing multiple leptons? Although very rare process, the production of leptons is calculated in SM with high precision. On detector side the leptons (electrons and muons) are easy to reconstruct and such a sample contains very little "non-lepton" background. This analysis has a very ambitious goal to test many final states at once, without over-tuning for a specific model. The second step would then be to test obtained results against models of composite structure of leptons or presence of heavy right handed neutrinos favored in seesaw theories. With this project, the student would gain close familiarity with modern experimental techniques (statistical analysis, SM background estimates, etc.), with Monte Carlo generators and the standard HEP analysis tools (ROOT, C++, etc.).

Contact: Olya Igonkina

ATLAS : Search for supersymmetric dark matter-like particles

Supersymmetry is a theory of physics beyond the Standard Model of particle physics that makes a link between fermions and bosons. Apart from many other attractive features, supersymmetry also predicts a particle that may be a candidate for dark matter. Such particles, and their related particles, may be produced at the LHC. Searching for them, however, is challenging. The production cross-sections are small, and the final states are difficult to measure, for example because the final state particles may have little energy, and are ignored by the ATLAS trigger and reconstruction software. In this project we will investigate the measurement of such particles, with the aim to improve the current ATLAS search strategy. You will then apply the improved analysis to the ATLAS data (to be) collected in 2016. In the project you will learn modern experimental analysis techniques, as well as programming in ROOT and C++.

Contact: Paul de Jong

ATLAS inner tracker upgrade

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.

Contact: Peter Vankov

ATLAS : Model testing for Beyond the Standard Model Higgs

Recently there's been a lot of excitement about hints for new Beyond the Standard Model (BSM) physics. When the search for the Higgs was ongoing we had a model to test possible bumps against, now we are looking for any new particle and there are many models available. Testing the newest results from the LHC is challenging because of low statistics and model uncertainties. In this project we will investigate different BSM Higgs models that could possible explain the newest results of the LHC. For this we will use the data collected in 2015 and the data that will be collected in 2016. In the end we will set limits on the tested models (or discover a new particle). During the project you will learn modern experimental analysis techniques as well as programming.

Contact: Wouter Verkerke, Lydia Brenner

KM3NeT : Reconstruction of first neutrinos in KM3NeT

The neutrino telescope KM3NeT is under construction in the Mediterranean Sea aiming to detect cosmic neutrinos. Its first string with sensitive photodetectors has been deployed end of 2015, in total 30 will be deployed til end of 2017. Already these few strings provide for the option to reconstruct in the detector the abundant muons stemming from interactions of cosmic rays with the atmosphere and to identify neutrino interactions. The performance and calibration of the detector will be evaluated also in comparison with simulations. Procedures to identify and also optimally reconstruct the directions of the muons and neutrinos will be developed to verify the performance and potential of the detector and to pave the path towards the neutrino astronomy. Programming skills are essential, mostly root and C++ will be used.

Contact: Ronald Bruijn

Neutrino mass hierarchy with KM3NeT/ORCA

Neutrinos exist in three flavors and are known to oscillate between flavors whereby the detected flavor depends on the (partly) known oscillation parameters, the mass differences, their energy and travel length. The neutrino telescope KM3NeT is planning for a dedicated set of detection units in order to pursue an oscillation measurement of an unprecedented precision using neutrinos from atmospheric interactions and with this enabling the measurement of the so far still unknown neutrino mass hierarchy. The measurement of this subtle effect requires unprecedented precision in the reconstruction and identification of the flavor, energy and direction. Various projects are available in the reconstruction and evaluation of the mass hierarchy using dedicated simulations. Programming skills are essential, mainly C++ and root will be used.

Contact: Aart Heijboer

All-flavor-neutrino analysis of ANTARES data

The ANTARES neutrino telescope has been taking data continuously since 2007. Most analyses of the data have been performed using the signature of a muon neutrino interaction whereby a long track can be reconstructed in the detector. Recent developments allowed for the first time also the reconstruction of a cascade signature in the detector at high angular resolution so that also electron and tau neutrino interactions can be detected (here these two are not distinguishable from each other). A search for neutrinos from cosmic sources on the first 6 years of data has by now been accomplished using this new reconstruction. In this project this search will be continued and exploited also on 2 more years of data for a dedicated optimized analysis of the Galactic Center to probe the possible neutrino emission from this highly interesting region. Programming skills are essential, mainly C++ and root will be used. Also other options for analyses of the ANTARES data are available.

Contact: Dorothea Samtleben

Particle Polarization in Strong Magnetic Fields

When two atomic nuclei, moving in opposite directions, collide off- center then the Quark Gluon Plasma (QGP) created in the overlap zone is expected to rotate. The nucleons not participating in the collision represent electric currents generating an intense magnetic field. The magnetic field could be as large as 10^{18} gauss, orders of magnitude larger than the strongest magnetic fields found in astronomical objects. Proving the existence of the rotation and/or the magnetic field could be done by checking if particles with spin are aligned with the rotation axis or if charged particles have different production rates relative to the direction of the magnetic field. In particular, the longitudinal and transverse polarisation of the Lambda^0 baryon will be studied. This project requires some affinity with computer programming.

Contact: P. Christakoglou, P. Kuijer

Forward Particle Production from the Color Glass Condensate

It has been proposed that a new state of matter (the color-glass condensate, or CGC) may provide a universal description of hadronic collisions (e.g. proton-proton collisions) at very high energy. The CGC may be seen as the classical field limit of Quantum Chromodynamics, and a framework for calculating observables from this state has been developed. Several measurements are consistent with the assumption of a CGC, but no experimental proof exists so far. In this project we intend to perform a systematic study of the sensitivity to the CGC of different possible measurements at the LHC. The work will be performed in close collaboration with an external world expert in this field. It is advantageous to have a good background in theoretical physics. (contact: T. Peitzmann, M. van Leeuwen) Blast-Wave Model in Heavy-Ion collisions The goal of heavy-ion physics is to study the Quark Gluon Plasma (QGP), a hot and dense medium where quarks and gluons move freely over large distances, larger than the typical size of a hadron. Hydrodynamic simulations expect that the QGP will expand under its own pressure, and cool while expanding. These simulations are particularly successful in describing some of the key observables measured experimentally, such as particle spectra and elliptic flow. A reasonable reproduction of the same observables is also achieved with models that use parameterisations that resemble the hydrodynamical evolution of the system assuming a given freeze-out scenario, usually referred to as blast-wave models. The goal of this project is to work on different blast wave parametrisations, test their dependence on the input parameters and extend their applicability by including more observables studied in heavy-ion collisions in the global fit.

Contact: P. Christakoglou, P. Kuijer

Energy Loss of Energetic Quarks and Gluons in the Quark-Gluon Plasma

One of the ways to study the quark-gluon plasma that is formed in high-energy nuclear collisions, is using high-energy partons (quarks or gluons) that are produced early in the collision and interact with the quark-gluon plasma as they propagate through it. There are several current open questions related to this topic, which can be explored in a Master's project. For example, we would like to use a new Monte Carlo generator model (JEWEL) of the collision to see whether we can measure the shape of the collision region using measurements of hadron pairs. In the project you will collaborate with one the PhD students in our group to use the model to generate predictions of measurements and compare those to data analysis results. Depending on your interests, the project can focus more on the modeling aspects or on the analysis of experimental data from the ALICE detector at the LHC.

Contact: M. van Leeuwen

Chiral Magnetic Effect and the Strong CP Problem

Within the Standard Model, symmetries, such as the combination of charge conjugation (C) and parity (P), known as CP-symmetry, are considered to be key principles of particle physics. The violation of the CP-invariance can be accommodated within the Standard Model in the weak and the strong interactions, however it has only been confirmed experimentally in the former. Theory predicts that in heavy-ion collisions gluonic fields create domains where the parity symmetry is locally violated. This manifests itself in a charge-dependent asymmetry in the production of particles relative to the reaction plane, which is called Chiral Magnetic Effect (CME). The first experimental results from STAR (RHIC) and ALICE (LHC) are consistent with the expectations from the CME, but background effects have not yet been properly disentangled. In this project you will develop and test new observables of the CME, trying to understand and discriminate the background sources that affects such a measurement.

Contact: P. Christakoglou, P. Kuijer

Quantum Coherence in Particle Production with Intensity Interferometry

Intensity interferometry – also known as HBT-effect or Bose-Einstein-correlations – is a method to study the space-time structure of the particle-emitting source in high-energy physics. The main interest so far has been on the width of correlation functions in momentum space, which reflects the space-time information. The strength of the correlation also carries information, but this has been ignored by many people. The correlation strength is in particular influenced by the degree of coherence of particle production. Recently new studies have been performed to extract this degree of coherence, however, many other effects might distort such a measurement, in particular the production of pions via resonance decay. In this project we will study the role of resonance decays for a measurement of coherence in intensity interferometry and try to establish possible correction methods for any distortions they may cause. We will perform theoretical model calculations with Monte-Carlo simulation methods.

Contact: T. Peitzmann

Higher Harmonic Flow

When two ions collide, if the impact parameter is not zero, the overlap region is not isotropic. This spatial anisotropy of the overlap region is transformed into an anisotropy in momentum space through interactions between partons and at a later stage between the produced particles. It was recently realized that the overlap region of the colliding nuclei exhibits an irregular shape. These irregularities originate from the initial density profile of nucleons participating in the collision which is not smooth and is different from one event to the other. The resulting higher order flow harmonics (e.g. v3, v4, and v5, usually referred to as triangular, quadrangular, and pentangular flow, respectively) and in particular their transverse momentum dependence are argued to be more sensitive probes than elliptic flow not only of the initial geometry and its fluctuations but also of shear viscosity over entropy density (η/s). The goal of this project is to study v3, v4, and v5 for identified particles in collisions of heavy-ions at the LHC.

Contact: P. Christakoglou, P. Kuijer

A New Detector for Very High-Energy Photons: FoCal

High-energy photons are important messenger particles in particle physics. In particular direct photons (i.e. directly produced from elementary scattering processes) are interesting, but it is a difficult task to discriminate them from the photons originating from particle decays. Existing detector have limited capabilities for such a discrimination, in particular at the highest energies. Our institute has pioneered a detector based on a new concept, a digital pixel calorimeter with Si-sensors of unprecedented granularity. First proof-of-principle measurements have already been performed. In this project we will study the performance of a particular detector design for measurements of direct photons at the LHC and optimize the design parameters for such a measurement. Performance studies for other measurements – e.g. jets, J/ψ, or ϒ particles – may be carried out in addition.

Contact: T. Peitzmann M. van Leeuwen

Thermal Photon Emission: Quark-Gluon Plasma or Hadron Gas?

Recently, measurements of thermal photon emission in high-energy nuclear collisions have been performed at RHIC and at LHC. It is generally believed that a quark-gluon plasma equation of state is the natural description of the hot initial phase of these collisions, and so far only theoretical model calculations including such a phase have been compared to those measurements. In this project we will revisit hadron gas models and try to reproduce the thermal photon yield together with other observables. In this work we will use and possibly modify Monte Carlo implementations of relativistic hydrodynamics, tune it to existing data of hadron production and then estimate the photon production from the same model. The model implementation will be based on previous work of external theoretical colleagues and will be carried out in collaboration with them.

Contact: T. Peitzmann

A New Detector for Proton Therapy and Proton Computed Tomography

Conventional imaging of humans in medical treatment relies mostly on electromagnetic radiation (CT, MRT) or positrons (PET). A recently proposed new imaging strategy, in particular in the context of proton therapy for cancer treatment, is to use proton beams. Current detectors for the scattered protons have severe limitations, in particular for their precision and measurement times. New development of intelligent Si-sensors in particle physics offer possibilities to develop much more efficient detectors for such proton CT measurements. We will perform R&D on the use of new silicon pixel detectors developed in the context of the ALICE experiment at CERN for such medical applications. Studies will include Monte-Carlo simulations of a possible detector setup and measurements with the first samples of the appropriate silicon sensors, which will become available in early 2016. The project will be carried out in the context of a scientific collaboration with Bergen University, Norway.

Contact: T. Peitzmann

Medical X-ray Imaging

With the upcoming of true multi-threshold X-Ray detectors the possibilities for Spectral Imaging with low dose, including spectral CT, is now a reality around the corner. The Medipix3RX chip, from the Medipix Collaboration (CERN) features up to 8 programmable thresholds which can select energy bins without a threshold scan. A number of projects could be derived from the R&D activities with the Medipix3RX within the Nikhef R&D group on X-ray imaging for medical applications:

• Medipix3RX characterization in all its operation modes and gains.
• Spectral CT and scarce sampling 3D reconstruction
• Charge sharing: the charge-sum capabilities of the chip can be exploited to further understand the problem of charge sharing in pixelized detectors. A combination of the characterization of the charge-summing mode plus the use of both planar, and 3D sensors, at the light of MC simulation, could reveal valuable information about charge sharing.

Contact: John Idarraga,Niels van Bakel

Compton camera

In the Nikhef R&D group we develop instrumentation for particle physics but we also investigate how particle physics detectors can be used for different purposes. A succesfull development is the Medipix chip that can be used in Xray imaging. For use in large scale medical applications compton scattering limits however the energy resolving possibilities. You will investigate whether it is in principle possible to design a Xray application that detects the compton scattered elctron and the absorbed photon. Your ideas can be tested in practice in the lab where a Xray scan can be performed.

Contact: Els Koffeman

The Modulation experiment

There exist a few measurements that suggest an annual modulation in the activity of radioactive sources. With a few groups from the XENON collaboration we have developed four sets of table-top experiments to investigate this effect on a few well known radioactive sources. The experiments are under construction in Purdue University (USA), a mountain top in Switzerland, a beach in Rio de Janeiro and the last one at Nikhef in Amsterdam. We urgently need a master student to (1) do the final commissioning of the experiment, (2) collect the 1st big data set, and (3) analyse the first data. We are looking for an all-round physicist with interest in both lab-work and data-analysis. The student will directly collaborate with the other groups in this small collaboration (around 10 people), and the goal is to have the first publication ready by the end of the project.

Contact: Auke Colijn

Acoustic detection of ultra-high energy cosmic-ray neutrinos

The study of the cosmic neutrinos of energies above 10^17 eV, so-called ultra-high energy neutrinos, provides a unique view on the universe and may provide insight in the origin of the most violent sources, such as gamma ray bursts, supernovae or even dark matter. The energy deposition of cosmic neutrinos in water induces a thermo-acoustic signal, which can be detected using sensitive hydrophones. The expected neutrino flux is however extremely low and the signal that neutrinos induce is small. TNO is presently developing sensitive hydrophone technology that is based on fiber optics. Optical fibers form a natural way to create a distributed sensing system. Using this technology a large scale neutrino telescope can be built in the deep sea. TNO is aiming for a prototype hydrophone which will form the building block of a future telescope.

Students have the possibility to participate to this project is the following ways: (i) Modeling of cosmic rays induced acoustic signal in a neutrino telescope. Keywords: Cosmic rays, Monte Carlo, signal processing, telescope optimization. (ii) Testing and optimization of fiber optical hydrophone for a large scale neutrino telescope. Keywords: Experimental, physics, system design.

The work will be (partly) executed in Delft.

Contact: Ernst-Jan Buis

A Scintillator Fibers Tracker

The LHCb collaboration is upgrading the present tracking system constructing a new tracker based on scintillating fibers combined with silicon photo-multipliers (SiPM): the SciFi Tracker! Nikhef plays a key role in the project, as we will build the SciFi fibers modules, the cold-box enclosure housing the SiPMs, and a large part of the on-detector electronics. In all these areas, interesting test hardware and software has to be realized, and several research topics for a Master project are available, taking the student in contact with state-of-the-art particle detectors, in a large team of physicists and engineers. Possible collaborations with the Nikhef R&D group can also be envisaged.

Contact: Antonio Pellegrino

Measurement of the Branching Ratio of Lambda_b --> p Ds+

This project aims to measure the branching fraction of the decay Lb->p Ds+. The decay Lb->p Ds+ is quite rare, because it occurs through the transition of a b-quark to a u-quark. It has not been measured yet (although some LHCXb colleagues claim to have seen it in the past). This decay is interesting, because 1) It is sensitive to the CKM-element Vub, which determination is heavily debated. 2) It can quantify non-factorisable QCD effects in b-baryon decays. The decay is closely related to B0->pi-Ds+, which proceeds through a similar Feynman diagram. Also the final state of B0->pi-Ds+ is almost identical to Lb->p Ds+. The aim is to determine the relative branching fraction of Lb->pDs+ with respect to B0->D+pi- decays, in close collaboration with the PhD (who will study BR(B0->pi-Ds+)/BR(B0->D+pi-) ). The aim is that this project results in a journal publication on behalf of the LHCb collaboration. For this project computer skills are needed. The ROOT programme and C++ and/or Python macros are used. This is a project that is closely related to previous analyses in the group. Weekly video meetings with CERN coordinate the efforts with in the LHCb collaboration.

Relevant information:

[1] R.Aaij et al. [LHCb Collaboration], ``Study of the kinematic dependences of Lambda_b production in pp collisions and a measurement of the Lambda_b->Lambda_c pi branching fraction, JHEP 08 (2014) 143 [arXiv:1405.6842 [hep-ex]]. [2] R.Aaij et al. [LHCb Collaboration], ``Determination of the branching fractions of B0s->DsK and B0->DsK, JHEP 05 (2015) 019 [arXiv:1412.7654 [hep-ex]]. [3] R. Fleischer, N. Serra and N. Tuning, ``Tests of Factorization and SU(3) Relations in B Decays into Heavy-Light Final States, Phys. Rev. D 83, 014017 (2011) [arXiv:1012.2784 [hep-ph]]. [4] K. de Bruyn, R. Fleischer, R. Knegjens, M. Merk, M. Schiller and N. Tuning, ``Exploring Bs -> Ds(*)K Decays in the Presence of a Sizable Width Difference Delta Gamma_s, Nucl. Phys. B 868, 351 (2013) [arXiv:1208.6463 [hep-ph]].

Contact: Niels Tuning and Lennaert Bel and Mick Mulder

A search for heavy neutrinos in the decay of W bosons at LHCb

Neutrinos are arguably the most mysterious of all known fundamental fermions as they are both much lighter than all others and only weakly interacting. It is thought that the tiny mass of neutrinos can be explained by their mixing with so-far unknown, much heavier, neutrino-like particles. In this research proposal we look for these new neutrinos in the decay of the SM W-boson using data with the LHCb experiment at CERN. The W boson is assumed to decay to a heavy neutrino and a muon. The heavy neutrino subsequently decays to a muon and a pair of quarks. Both like-sign and opposite-sign muon pairs will be studied. The result of the analysis will either be a limit on the production of the new neutrinos or the discovery of something entirely new.

Contact: Wouter Hulsbergen and Elena Dall'Occo

A search for Majorana neutrinos in the decay of Bc mesons at LHCb

Neutrinos can either be their own anti-particles, in which case they are called "Majorana" particles, or Dirac fermions. It is thought that the tiny mass of neutrinos can be explained by their mixing with so-far unknown, much heavier, neutrino-like particles. LHCb has looked for off-shell Majorana neutrinos in the decays B+->pi-mu+mu+ and B+->D(*)-mu+mu+. Both decays suffer from suppression from Cabibbo-Kobayashi-Maskawa matrix elements, or from low reconstruction efficiencies. Although its production rate is much lower, the Bc meson provides a potentially more promising decay channel: Bc->J/psimu+mu+pi-. The Master student will design and optimise a selection, study potential backgrounds and perform a search in view of setting a stringent limit, or an observation of new physics.

arXiv:1401.5361 [hep-ex]. arXiv:1201.5600 [hep-ex]. arXiv:11602.09112 [hep-ph]

Contact: Patrick Koppenburg and Flavio Archilli