The LHC at CERN began operation in 2009. It collides protons
at a centre-of-mass energy of up to 14 TeV and is the highest energy machine in the world. The CMS experiment at the LHC is built to search for the
Higgs Boson and all sorts of other wierd and wonderful things that might exist.
I am currently working on searches for long-lived particles, such as heavy neutral leptons, using a tagger based on a Deep Neural Network and searches for Dark Matter in the Vector Boson Fusion production channel.
I lead the UK project to upgrade the CMS detector for High-Luminosity LHC. The CMS UK groups are involved in international projects to upgrade the CMS tracker, Level-1 trigger and barrel calorimeter and in the project to construct a high-granularity tracking endcap calorimeter.
From 2016 - 2020 I was Project Manager for the CMS Level-1 Trigger system. Responsible for all aspects of the project, including the day-to-day operation, planning and setting priorities and long term upgrades for High-Luminosity LHC, planned for 2026 onwards. Currently I chair the CMS Trigger and DAQ (TriDAS) Institution Board. I also led the CMS UK Level-1 Trigger upgrade project for several years.
In 2015 and 2016 I took responsibility for coordinating and commissioning the Phase 1 upgrade to the calorimeter trigger system and coordinating UK trigger upgrade activities both for Phase 1 and Phase 2 upgrades.
I worked on the global calorimeter trigger from 2006 to 2015. I wrote parts of the simulation of the trigger, tools to analyse the performance of the trigger and optimise algorithms, and led commissioning of the trigger, writing many of the software tools required for commissioning. Later I became Project Manager of the GCT with overall responsibility for the project
In 2014 and 2015 I led the Hadron Calorimeter (HCAL) Detector Performance Group Trigger sub-group, preparing the HCAL for the restart of the LHC after Long Shutdown 1 and future upgrades.
I am a member of the Data Aquisition System (DAQ) consortium, where I coordinate the Control, Configuration and Monitoring system.
ZEUS
The HERA collider at the
DESY laboratory in Hamburg
collided electrons or positrons with protons from 1992 to 2007.
In scattering high energy electrons or positrons off protons the quarks that make up the proton
can be studied down to distances of 10-18 m. The ZEUS
experiment studied events from these collisions, reconstructing the particles thrown out when the
proton is broken up in order to measure the structure of the proton. A poster I made about studying
the structure of the proton with the ZEUS experiment is here.
As everyone knows the devil's in the detail, so to protect members of the public from the full horror
links marked with a are only accessible to members of the ZEUS collaboration.
My last contribution to ZEUS was the measurement of electron-proton charged current deep inelastic scattering
cross sections with longitudinally polarised electron beams, which is now published (see publications page).
The first measurements from HERA II were of positron-proton charged and neutral current deep inelastic scattering
cross sections with a longitudinally polarised positron beam. This was the first time that the dependence of these
cross sections on longitudinal polarisation had been measured and details can be found in
this entry in the ZEUS database.
All the gory details are available to ZEUS members
here.
Some useful links to the HERA I results are below.
The electron running in 1998 and 1999 allowed us to make the first measurements of the high Q2 cross sections
in electron-proton collisions and to extract the structure function xF3 from the neutral current cross sections.
The positron running in 1999 and 2000
gave us the largest data sample of positron-proton collisions in HERA I and allowed us to make the most accurate
measurements of the high Q2 cross sections to date. In addition the large data sample made it possible to
improve the calibration of the calorimeter energy scale and energy flow, yielding smaller systematic
uncertainties than previous analyses. Details can be found below.
The structure function measurements and also measurements of jet production can be used to
constrain the parton density functions (PDFs) in the proton and determine the strong coupling constant. Results
from these analyses can be found in the HEPDATA database.
Trigger studies
I worked for a long time on triggers for structure functions and exotic processes. Some details are below.
The ZEUS central tracking detector (CTD) was a large cylindrical drift chamber. As a Ph.D. student I
worked on the monitoring of the quality of the CTD data. See the
CTD data quality monitoring pages for details.
Later I was an on-call expert for the CTD and grew used to being woken up in the middle
of the night. See the CTD online help pages
for details. I also designed and implemented a database to keep track of the electronics cards for the
CTD based on mySQL and PHP. You can find it
here.
Imperial College built the high voltage system for the CTD and I helped to maintain it for several years. Probably only of interest to the connosieur the
CTD HV system pages.
HERA Transverse Polarimeter
The HERA transverse polarimeter (TPOL) measured the transverse polarisation of the HERA lepton beam
by shining a circularly polarised laser beam on the lepton beam and analysing the backscattered Compton photons.
As part of the HERA upgrade in 2001 - 2002 the TPOL was upgraded to provide a high precision
bunch-by-bunch measurement of the polarisation. Part of this upgrade was the development and installation
of a silicon strip detector to improve the accuracy of the measurement. I was involved in the development,
testing and installation of the silicon strip detector and later took responsibilty for commissioning
the detector and the analysis of the data. I also built a shadow system and a cosmic-ray muon test stand
at Imperial with the full silicon detector readout in order to test spares and improved electronics.
The silicon detector was based on sensors from the ATLAS experiment and the readout of the CMS experiment. More specifically the readout system with the APV25 readout chip.
The analysis of the data and the long road to the final polarisation measurements are documented on the Polarimeter Analysis page.
Results from the analysis of cosmic-muon events are here.
Data Science
I am a member of the Scientific Commitee of the Fast Machine Learning collaboration.
I collaborate with Maxeler Technologies/Groq and Altera on the application of accelerated dataflow platforms and tools to particle physics, previously through the ExCALIBUR-HEP and SWIFT-HEP projects.
CMS Collaboration, Search for low-mass hidden valley dark showers with displaced dimuons in proton-proton collisions at sqrt(s) = 13 TeV.
M. Barbone et al., Application of computational modelling to particle physics, Accepted by Comput. Phys. Commun. (2025).
S. Summers et al., Roadmap on Fast Machine Learning for Science, submitted to Machine Learning: Science and Technology (2025).
N. Anfimov et al., First demonstration of a combined light and charge pixel readout on the anode plane of a LArTPC, JINST 19 P11010 (2024).
P. Odagiu et al., Sets are All You Need: Ultrafast Jet Classification on FPGAs for HL-LHC, Mach. Learn.: Sci. Technol. 5 035017 (2024).
C. Brown et al., Quantum Pathways for Charged Track Finding in High-Energy Collisions, Front. Artif. Intell. 7:1339785 (2024).
CMS Collaboration, Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton, JHEP03 (2024) 105.
Z. Que et al., LL-GNN: Low Latency Graph Neural Networks on FPGAs for Particle Detectors, ACM Trans. Embedd. Comput. Syst., Vol. 23, No. 2, Article 17 (2024).
CMS Collaboration, Search for invisible decays of a Higgs boson produced via vector boson fusion with 138 fb−1 of proton-proton collisions at sqrt(s) = 13 TeV, Phys. Rev. D 105, 092007 (2022).
CMS Collaboration, Performance of the CMS Level-1 trigger in proton-proton collisions at sqrt(s) = 13 TeV, JINST 15 (2020) P10017.
CMS Collaboration, A deep neural network to search for new long-lived particles decaying to jets, Mach. Learn.: Sci. Technol. 1 035012 (2020).
CMS Collaboration, Search for natural and split supersymmetric scenarios in pp collisions at sqrt(s) = 13 TeV in all-jet final states, JHEP 05 (2018) 025.
R. Aggleton et al., An FPGA Based Track Finder for the L1 Trigger of the CMS Experiment at the High Luminosity LHC, JINST 12 (2017) P12019.
CMS Collaboration, A search for new phenomena in pp collisions at sqrt(s) = 13 TeV in final states with missing transverse momentum and at least one jet using the αT variable, Eur. Phys. J. C 77 (2017) 294.
CMS Collaboration, Search for top squark pair production in compressed-mass-spectrum scenarios in proton-proton collisions at sqrt(s) = 8 TeV using the αT variable, Phys. Lett. B 767 (2017) 403.
CMS Collaboration, The CMS trigger system, JINST 12 (2017) P01020.
CMS Collaboration, Searches for third generation squark production
in fully hadronic final states in proton-proton collisions at sqrt(s)=8 TeV, JHEP 06 (2015) 116.
CMS Collaboration, Search for supersymmetry in hadronic final states with missing transverse energy using the variables αT and b-quark multiplicity in pp collisions at 8 TeV, Eur. Phys. J. C73 (2013) no.9, 2568.
CMS Collaboration, Search for supersymmetry in final states with missing transverse energy and 0, 1, 2, or at least 3 b-quark jets in 7 TeV pp collisions using the variable αT, JHEP 1301 (2013) 077.
CMS Collaboration, Search for Supersymmetry at the LHC in Events with Jets and Missing Transverse Energy, Phys. Rev. Lett. 107 (2011) 221804.
Papers as convener of the CMS Supersymmetry Physics Analysis Group:
CMS Collaboration, Inclusive search for squarks and gluinos at sqrt(s) = 7 TeV, Phys. Rev. D 85, 012004 (2012).
CMS Collaboration, Search for Supersymmetry at the LHC in Events with Jets and Missing Transverse Energy, Phys. Rev. Lett. 107, 221804 (2011).
CMS Collaboration, Inclusive search for new physics at CMS with the jets and missing momentum signature, JHEP 1108:155 (2011).
CMS Collaboration, Search for New Physics in pp Collisions at sqrt(s) = 7 TeV in Events with a Single Lepton, Jets, and Missing Transverse Momentum, JHEP 1108:156 (2011).
CMS Collaboration, Search for Supersymmetry in pp Collisions at sqrt(s) = 7 TeV in Events with A Lepton, Photon, and Missing Transverse Energy, JHEP 1106:093 (2011).
CMS Collaboration, Search for Physics Beyond the Standard Model Using Multilepton Signatures in sqrt(s) = 7 TeV pp Collisions with the CMS Detector at the LHC, Phys. Lett. B704:411-433 (2011).
CMS Collaboration, Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy at the LHC, JHEP 1106:077 (2011).
CMS Collaboration, Search for Supersymmetry in Events with b Jets
and Missing Transverse Momentum at the LHC, JHEP 1107:113 (2011).
CMS Collaboration, Search for Physics Beyond the Standard Model in
Opposite-Sign Dilepton Events in pp Collisions at sqrt(s) = 7 TeV, JHEP 1106:026 (2011).
CMS Collaboration, A Search for Supersymmetry in pp Collisions at 7 TeV Using Events with Two Photons and Large Missing Transverse Energy, Phys. Rev. Lett. 106, 211802 (2011).
CMS Collaboration, Search for Supersymmetry in pp Collisions at 7 TeV in Events with Jets and Missing Transverse Energy, Phys. Lett. B698:196-218 (2011).
As chair or member of CMS analysis review committees:
CMS Collaboration, Search for Lepton Flavour Violation in the Top Quark Interaction with an Up-type Quark, a Muon, and a Tau, submitted to JHEP (as chair of the review committee)
CMS Collaboration, Performance of the CMS High Level Trigger during LHC Run-2, JINST 19 P11021 (2024). (as chair of the review committee)
CMS Collaboration, Search for new physics in multijet events with at least a photon and large missing transverse momentum in proton-proton collisions at 13 TeV, JHEP10 (2023) 046. (as chair of the review committee)
CMS Collaboration, Development of the CMS detector for the CERN LHC Run 3, JINST 19 P05064 (2024). (as member of the review committee)
CMS Collaboration, Search for top squarks in the four-body decay mode with single lepton final states in proton-proton collisions at √s=13 TeV, J. High Energ. Phys. 2023, 60 (2023). (as member of the review committee)
CMS Collaboration, Search for charged-lepton flavor violation in top quark production and decay in pp collisions at sqrt(s) = 13 TeV, J. High Energ. Phys. 2022, 82 (2022). (as chair of the review committee)
CMS Collaboration, Search for supersymmetry in proton-proton
collisions at 13 TeV in final states with jets and missing
transverse momentum, JHEP 10 (2019) 244. (as chair of the review committee)
CMS Collaboration, Search for supersymmetry in multijet events with missing transverse momentum in proton-proton collisions at 13 TeV, Phys. Rev. D96 (2017) no.3, 032003. (as chair of the review committee)
CMS Collaboration, Search for top quark decays via Higgs-boson-mediated flavor-changing neutral currents in pp collisions at sqrt(s) = 8 TeV, JHEP 1702 (2017) 079. (as member of the review committee and chair of one of the analyses merged to form the paper)
CMS Collaboration, Search for supersymmetry in the multijet and missing transverse momentum final state in pp collisions at 13 TeV, Phys. Lett. B758 (2016) 152-180. (as chair of the review committee)
CMS Collaboration, Searches for R-parity-violating supersymmetry in pp collisions at sqrt(s) = 8 TeV in final states with 0-4 leptons, Phys. Rev. D94 (2016) no.11, 112009. (as member of the review committee)
CMS Collaboration, Search for supersymmetry with photons in pp collisions at sqrt(s) = 8 TeV, Phys. Rev. D92 (2015) no.7, 072006. (as chair of the review committee)
CMS Collaboration, Search for anomalous production of events with three or more leptons in pp collisions at sqrt(s) = 8 TeV, Phys. Rev. D90 (2014) 032006. (as member of the review committee)
CMS Collaboration, Search for top squarks in R-parity-violating supersymmetry using three or more leptons and b-tagged jets, Phys. Rev. Lett. 111 (2013) no.22, 221801. (as chair of the review committee)
CMS Collaboration, Search for supersymmetry in events with photons and low missing transverse energy in pp collisions at sqrt(s) = 7 TeV, Phys. Lett. B719 (2013) 42-61. (as chair of the review committee)
CMS Collaboration, Search for new physics in events with photons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV, JHEP 1303 (2013) 111. (as chair of the review committee)
Older papers I have written or contributed to:
M. Ellis et al., The design, construction and performance of the MICE scintillating fibre trackers, Nucl. Inst. Meth. A659, 136 (2011).
CMS Collaboration, Performance of the CMS Level-1 Trigger during Commissioning with Cosmic Ray Muons, 2010 JINST 5 T03002.
ZEUS Collaboration, S. Chekanov et al., Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA, Eur. Phys. J. C 61, 223 (2009) and on the cover of Volume 61 Number 2 June 2009.
ZEUS Collaboration, S. Chekanov et al., Measurement of high-Q2
deep inelastic scattering cross sections with a longitudinally
polarised positron beam at HERA, Phys. Lett. B 637, 210 (2006).
ZEUS Collaboration, S. Chekanov et al., High-Q2 neutral current
cross section in e+p deep inelastic scattering at sqrt(s)=318 GeV,
Phys. Rev. D 70, 052001 (2004).
ZEUS Collaboration, S. Chekanov et al., Measurement of high-Q2
charged current cross sections in e+p deep inelastic scattering at
HERA, Eur. Phys. J. C 32, 1 (2003).
ZEUS Collaboration, S. Chekanov et al., Measurement of high-Q2 e-p
neutral current cross sections at HERA and the extraction of xF3, Eur. Phys. J. C 28, 175 (2003).
ZEUS Collaboration, S. Chekanov et al., Measurement of high-Q2
charged current cross sections in e-p deep inelastic scattering at
HERA, Phys. Lett. B 539, 197 (2002). Erratum in Phys. Lett. B 552, 308 (2003).
ZEUS Collaboration, J. Breitweg et al., Measurement of High Q2 Charged-Current e+p Deep Inelastic Scattering Cross Sections at HERA, Eur. Phys. J. C 12, 411 (2000). Erratum in Eur. Phys. J. C 27, 305 (2003).
The CMS Level-1 Trigger for LHC Run II
Proceedings of ICHEP 2016, The 38th International Conference on High Energy Physics, 3-10 August 2016, Chicago, U.S.A.
Searches for Supersymmetry and Dark Matter at CMS
Johns Hopkins 36th Workshop Latest News on the Fermi scale from LHC and Dark Matter searches, October 8 - November 30, 2012, The Galileo Galilei Institute for Theoretical Physics, Florence, Italy.
Presentation of search results in CMS
Searches for New Physics Mini-Workshop: Les Houches Recommendations for the Presentation of LHC Results, 13 February 2012, CERN, Switzerland.
Early SUSY searches at the LHC
Searching for SUSY at the LHC and interplay with astroparticle physics, Joint HEP-APP IOP meeting, 24 March 2010, Imperial College London.
I am the coordinator of fourth year (MSci) projects. More information may be found on the Blackboard page.
Advanced Particle Physics (2017-2020)
From 2017 to 2020 I taught the Advanced Particle Physics course. It's a fourth year option course covering the Standard Model and beyond. All the course notes and information may be found on the Blackboard page for the course.
Other teaching activities
In addtion to lecturing and project coordination I coordinate and demonstrate in the third year undergraduate laboratory, lead first and second year group tutorials, lead third year professional skills seminars, set comprehensives exam questions, mark MSci and BSc project reports, act as associate lecturer for several courses and I am a personal tutor.
Postgraduate teaching
MRes Machine Learning and Big Data in the Physical Sciences (2021-present)
I co-developed and teach the Accelerated processing for big data analysis course, which is part of the MRes in Machine Learning and Big Data in the Physical Sciences, and introduces accelerators in computing, covering typical architectures, such as GPUs and FPGAs, and the implementation of algorithms, focussing on typical machine learning cases
HEP group postgraduate admissions (2019-present)
I am co-chair of the HEP group postgraduate admissions team. Prospective Ph.D. students can find more details here and are welcome to contact me.
HEP group postgraduate lectures (2012-present)
From 2012 to 2018 I organised the Imperial HEP group's postgraduate lectures courses.
Information for students, including the timetable and lecture notes can be found here.
I currently set the syllabus for graduate lectures on instrumentation and serve on the organising committee for the U.K. Advanced Instrumentation course.
Some lectures I have given as various parts of the different courses are listed below.
A (very) brief course on deep inelastic scattering and some QCD. Another course (C7 (b)) covers non-perturbative and phenomenological aspects, like hadronisation and jets.
are only accessible to members of the ZEUS collaboration.