List of previous students

Nicola Orlando
Faten Hariri
Emma Kuwertz
Spyridon Argyropoulo
Sabrina Sacerdoti
Simone Amoroso
Jesper Roy Christiansen
Nathan Hartland
Christian Roehr
Benjamin Watt
Philip Ilten
Nishita Desai
Sercan Sen
Miroslav Myska
Sudha Ahuja
Holger Schulz
Avi Gershan
Aleksander Kusina
Magdalena Slawinska
Flavia Dias
Kenneth Wraight
Irais Bautista Guzman
Sparsh Navin
Paolo Francavilla
Riccardo Di Sipio
Seyi Latunde-Dada
Devdatta Majumder
Martijn Gosselink
Christopher Bignamini
Marek Schönherr
Michal Deak
Noam Hod
Florian Bechtel
Jonathan Ferland
Manuel Bähr
Alexander Flossdorf
Piergiulio Lenzi

Martijn Gosselink is a PhD student from NIKHEF, Amsterdfam, The Netherlands working on Atlas, on a four-month MCnet studentship in Lund.

After the startup of the LHC this year, first data from proton-proton collisions is expected to arrive in 2009. This will not only give the opportunity to study known Standard Model processes at a new energy regime but also to search for previously unobserved processes and possibly even to discover new physics. Monte Carlo event generators will play a crucial role in these activities: they reflect the present (lack of) understanding of the various processes as good as possible. Events at the LHC will typically involve many energetic jets in the final state. To improve predictions for the rates of these processes, much attention has lately gone into various techniques of merging parton shower with matrix element, eg. MLM matching, CKKW, CKKW-L.

In my PhD research I focus on events with missing transverse energy, an isolated lepton and multiple jets in the final state. A very good understanding of the production rates of these processes, such as W + n-jets and ttbar + n-jets, is needed to prepare a future search for ttH (which is the ultimate goal of the grant my research is part of). Those processes have namely very similar signatures and are therefore irreducible background to each other. I have been working on a ttbar cross section measurement at ATLAS for the commissioning phase. Part of this work was comparing MC@NLO with Alpgen to estimate the uncertainty on event selection efficiencies. In an attempt to improve event selection, I have done an additional study on using momentum fractions x1 and x2 to separate W + n-jets from ttbar + n-jets.

To benefit from the opportunity given by the MCnet and from the time remaining before arrival of the first data at LHC, I applied for a student ship for the standard period of four months. By doing so, I would like to extend my (technical) knowledge on Monte Carlo generator techniques, especially on the side of merging parton shower with matrix element. This goal could be reached by implementing such a technique in the ATLAS software framework, thereby making it available to the entire collaboration. The work would include the validation of the implementation by comparing results with other generators in the framework. Eventually, comparison with first data could be part of my future research after the student ship.

During the CTEQ-MCnet 2008 summer school in Debrecen, I developed a special interest in the CKKW-L method used within Ariadne. This method includes, unlike other generators, corrections for small values of x la BFKL. Resulting pT spectra for W + n-jets at LHC energies seem to be harder. This might turn out to be an important difference.