Difference between revisions of "Master student Projects"

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! style="background:#3399ff;" | <font color=#ffffff> 1) Bs->mumu normalization and B mesons hadronization probabilities </font>
+
! style="background:#3399ff;" | <font color=#ffffff> 1) Bs->mumu and Bd->mumu normalization and B mesons hadronization probabilities </font>
 
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''' Research description: '''
 
''' Research description: '''
  
−
The large-acceptance tracker of LHCb will be replaced by a detector
+
The measurement of the Bs-> mu mu and Bd->mu mu decays
−
with increased rate capabilities during next LHC long shutdown in 2019.
+
is one of the flagships of the LHCb experiment, the latest result in
−
The new detector will be based on arrays of scintillating fibers (SciFi) with
+
combination with CMS has recently been published on Nature.
−
0.25 mm diameters, read out by silicon photo-multipliers (SiPMs).
+
The aim of this project is to study the yields of other decays
−
The processing of the SiPM signals (the whole detector will consist of
+
with a J/Psi in the final state, like B+ -> J/Psi K+ and  Bs-> J/Psi Phi,
−
589,824 SiPM channels) in the on-detector electronics will proceed in
+
that can be detected triggering on the muons decay products of the J/Psi.
−
two stages: first an application-specific integrated circuit will amplify
+
These yields are a crucial input to obtain the Bs-> mu mu and Bd->mu mu decays
−
and shape the signal and a set of comparators will digitize a two-bits
+
branching fraction as they provide a relative normalization.
−
information per channel; then dedicated FPGAs will reduce the data size
+
Moreover, in order to use Bd decays to normalize the Bs-> mu mu yields
−
and suppress noise through a data-clustering algorithm.
+
we need to measure the relative probabilities for a b quark to hadronize
 +
into a Bs (f_s) or a Bd (f_d) meson, that can also be obtained from
 +
B+ -> J/Psi K+,  Bs-> J/Psi Phi and Bd-> J/Psi K* decays.
 +
The ratio f_s/f_d is not a constant and is therefore important
 +
to measure it as a function of both the energy in the center of mass
 +
of the pp collision and the B mesons kinematics. The combination
 +
of previous data at 7 and 8 TeV and data at 13 TeV from the LHC 2015 run
 +
will provide us important new insight and is a result worth a journal
 +
publication in his own right.
  
−
The Nikhef group is responsible for this second stage, namely for the
+
For this project some programming skills are needed (PYTHON or C++).
−
implementation of the clusterization algorithm and for the design, production
+
Some initial knowledge of the ROOT analysis framework is also useful.
−
and testing of the on-detector PCBs hosting the FPGAs running the algorithm.
+
The student will perform his research in a group consisting of two seniors and two Ph.D. students
−
This master project will contribute to this R&D in two main ways.
+
engaged in the study of very rare decays of the B mesons to di-muon final states and the search
−
On the one hand, supporting the Nikhef electronics department in the
+
for lepton-flavor violating final states (e.g. electron-muon).
−
development of the code for the clusterization FPGA, providing a computer
 
−
emulation of the algorithm based on C++ code and a test bench capable of
 
−
processing the same data processed by the FPGA and of comparing the results.
 
−
On the other, participating to the design of an automated test system to
 
−
diagnose and characterize the SciFi on-detector electronics through the
 
−
injection of SiPM-like current pulses, in particular writing control software
 
−
and ROOT software to analyze the test data and diagnose faults.
 
−
 
 
−
For this project computing skills are needed (C++ and ROOT); an interest
 
−
for digital electronics is welcome (with the option of learning the basic
 
−
of VHDL programming). The student will perform his research in a group
 
−
consisting of two seniors, one Ph.D. student and an electronic engineer.
 
−
 
 
−
''' Relevant information: '''
 
−
 
 
−
LHCb Tracker Upgrade Technical Design Report [https://cds.cern.ch/record/1647400 CERN-LHCC-2014-001]
 
−
 
 
−
 
 
−
 
 
−
{| border="1" cellpadding="2" cellspacing="0"
 
−
|-
 
−
! style="background:#3399ff;" | <font color=#ffffff> 2) Detector Electronics & Data acquisition for the LHCb Scintillating Fiber Tracker </font>
 
−
|}
 
−
 
 
−
''' Supervisors:''' Antonio Pellegrino (physicist), Wilco Vink (engineer)
 
−
 
 
−
''' Research description: '''
 
−
 
 
−
The large-acceptance tracker of LHCb will be replaced by a detector
 
−
with increased rate capabilities during next LHC long shutdown in 2019.
 
−
The new detector will be based on arrays of scintillating fibers (SciFi) with
 
−
0.25 mm diameters, read out by silicon photo-multipliers (SiPMs).
 
−
The processing of the SiPM signals (the whole detector will consist of
 
−
589,824 SiPM channels) in the on-detector electronics will proceed in
 
−
two stages: first an application-specific integrated circuit will amplify
 
−
and shape the signal and a set of comparators will digitize a two-bits
 
−
information per channel; then dedicated FPGAs will reduce the data size
 
−
and suppress noise through a data-clustering algorithm.
 
−
 
 
−
The Nikhef group is responsible for this second stage, namely for the
 
−
implementation of the clusterization algorithm and for the design, production
 
−
and testing of the on-detector PCBs hosting the FPGAs running the algorithm.
 
−
This master project will contribute to this R&D in two main ways.
 
−
On the one hand, supporting the Nikhef electronics department in the
 
−
development of the code for the clusterization FPGA, providing a computer
 
−
emulation of the algorithm based on C++ code and a test bench capable of
 
−
processing the same data processed by the FPGA and of comparing the results.
 
−
On the other, participating to the design of an automated test system to
 
−
diagnose and characterize the SciFi on-detector electronics through the
 
−
injection of SiPM-like current pulses, in particular writing control software
 
−
and ROOT software to analyze the test data and diagnose faults.
 
−
 
 
−
For this project computing skills are needed (C++ and ROOT); an interest
 
−
for digital electronics is welcome (with the option of learning the basic
 
−
of VHDL programming). The student will perform his research in a group
 
−
consisting of two seniors, one Ph.D. student and an electronic engineer.
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''

Revision as of 14:01, 22 May 2015

Projects for Master students in the Nikhef B-physics (LHCb) group

date: May 2015

This is an overview with all available Master student projects in the Nikhef B-physics (LHCb) 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 B-physics group leader:

Marcel Merk [e-mail: i93_at_nikhef.nl, Tel 020-5925107, Nikhef room N2xx]

For an overview of the theses written in the Nikhef B-physics group you can look at the Nikhef LHCb theses page



Master projects in the Nikhef B-physics group

J/psi phi is a flagship analysis in the LHCb experiment. However, no-one in LHCb has tested whether CPT symmetry is violated. CPT symmetry is tightly connected to the principle of Lorentz invariance. Lorentz invariantz violation would become visible if the decay rate would show any dependency to a fixed direction in space. In this project the CP violation analysis is extended to test for Lorentz Invariance violation.

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 the larger effort at Nikhef (~5 people) of measuring phi_s with Bs->J/psiPhi decays. Weekly video meetings with CERN coordinate the efforts within the LHCb collaboration.


Relevant information:

Belle Collaboration: arXiv:1203.0930v2, Search for Time-Dependent CPT Violation in Hadronic and Semileptonic B Decays

End comment Niels Nov 2014 -->




1) Bs->mumu and Bd->mumu normalization and B mesons hadronization probabilities

Supervisors: Antonio Pellegrino (physicist)

Research description:

The measurement of the Bs-> mu mu and Bd->mu mu decays is one of the flagships of the LHCb experiment, the latest result in combination with CMS has recently been published on Nature. The aim of this project is to study the yields of other decays with a J/Psi in the final state, like B+ -> J/Psi K+ and Bs-> J/Psi Phi, that can be detected triggering on the muons decay products of the J/Psi. These yields are a crucial input to obtain the Bs-> mu mu and Bd->mu mu decays branching fraction as they provide a relative normalization. Moreover, in order to use Bd decays to normalize the Bs-> mu mu yields we need to measure the relative probabilities for a b quark to hadronize into a Bs (f_s) or a Bd (f_d) meson, that can also be obtained from B+ -> J/Psi K+, Bs-> J/Psi Phi and Bd-> J/Psi K* decays. The ratio f_s/f_d is not a constant and is therefore important to measure it as a function of both the energy in the center of mass of the pp collision and the B mesons kinematics. The combination of previous data at 7 and 8 TeV and data at 13 TeV from the LHC 2015 run will provide us important new insight and is a result worth a journal publication in his own right.

For this project some programming skills are needed (PYTHON or C++). Some initial knowledge of the ROOT analysis framework is also useful. The student will perform his research in a group consisting of two seniors and two Ph.D. students engaged in the study of very rare decays of the B mesons to di-muon final states and the search for lepton-flavor violating final states (e.g. electron-muon).

Relevant information:

LHCb Tracker Upgrade Technical Design Report CERN-LHCC-2014-001


2) Measurement of BR(B0->pi-Ds+) and BR(Bs->Ds-*pi+)/BR(Bs->Ds-pi+)

Supervisors: Niels Tuning (staf), Lennaert Bel (PhD) ?, Mick Mulder (PhD) ?

Research description:

This project aims to measure the branching fraction of the decay B0->pi-Ds+. The decay B0->pi-Ds+ is quite rare, because it occurs through the transition of a b-quark to a u-quark. It has been measured at the B-factories only at modest precision (~12%). This decay is interesting, because
1) It is sensitive to the CKM-element Vub, which determination is heavily debated.
2) It can be used to determine the ratio r_pi=B0->pi-D+/B0->D-pi+ which in turn is needed for CP violation measurements.
3) It can quantify non-factorisable QCD effects in certain B-decays.

The experimental challenge is to understand the background from e.g. Bs->Ds*pi decays. The aim is to also determine the relative branching fraction of Bs->Ds*pi relative to Bs->Dspi decays. This can is useful, because
1) It helps in the measurement of B0->pi-Ds+
2) It might quantify the magnitude of the ratio of form factors F(Bs->Ds*)/F(Bs->Ds*)

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 three important analyses in the group:
1) Measurements of fs/fd with hadronic Bs->DsPi decays,
2) Time dependent CP violation analysis of Bs->DsK decays.
Weekly video meetings with CERN coordinate the efforts with in the LHCb collaboration.

Relevant information:

[1] R.Aaij et al. [LHCb Collaboration], ``Determination of the branching fractions of B0s->DsK and B0->DsK, Submitted to JHEP [arXiv:1412.7654 [hep-ex]].

[2] 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]].

[3] 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 ??s, Nucl. Phys. B 868, 351 (2013) [arXiv:1208.6463 [hep-ph]].

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