Imperial College London

Alexander Tapper

Faculty of Natural SciencesDepartment of Physics

Professor of Physics



+44 (0)20 7594 1551a.tapper Website




508Blackett LaboratorySouth Kensington Campus





Particle physics is about understanding what our Universe is made of and how it came to be as it is today. After centuries of study we know that there are two kinds of matter, leptons and quarks, and that there are four forces that mediate their interactions: the electromagnetic, the strong, the weak and the gravitational force. This knowledge of fundamental particles and the interactions between them forms what is known as the Standard Model of particle physics.

Despite its overwhelming success, the Standard Model leaves many fascinating questions unanswered. What is the reason for the hierarchy of particle masses we observe? What is the origin of the huge matter-antimatter imbalance in the universe? Why is gravity so much weaker than the other forces? Why do we observe three generations of quarks and leptons? What is the origin of Dark Matter? It’s clear that the Standard Model cannot be the complete picture, but what would the bigger picture look like? and how can we find out?

I have been involved in several different aspects of research in large particle physics experiments. The majority of my work has been on data analysis, but I have also been closely involved in the design, commissioning and operation of the complex detectors typical of particle physics experiments. In addition I have worked in the management of the CMS and ZEUS experiments, coordinating scientific priorities and planning future research programmes. The focuses of my current research are searches for new physics and the trigger system of the CMS experiment at the Large Hadron Collider at CERN and the design of the DUNE experiment.

I also have a general interest in data science, and have established an initiative to apply the data processing techniques developed in particle physics more widely, including collaborations with industrial partners and projects with colleagues from the Imperial Computer Science department.

The CMS experiment

I lead the Imperial CMS group and am Principal Investigator of the CMS UK Upgrade project. I also serve as chair of the CMS Trigger and Data Acquisition Institution Board.

From 2016-2020 I was Project Manager for the CMS Level-1 Trigger system. I was 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.

In 2012 and 2013 I coordinated the project to upgrade the CMS Level-1 Trigger system to cope with the higher luminosity delivered by the LHC from 2015 onwards. We wrote a Technical Design Report which I defended through several stages of international review successfully.

In 2010 and 2011 I was co-convenor of the CMS supersymmetry physics analysis group. Under my leadership the group analysed the 2010 and 2011 LHC data for signs of physics beyond the Standard Model, producing some of the most stringent limits on supersymmetry in the world and publishing several ground-breaking papers. I was responsible for all aspects of the group’s work, from the overall scientific strategy to the scope and detailed content of the papers.


The Deep Underground Neutrino Experiment (DUNE) is a long baseline neutrino experiment, based at Fermilab near Chicago and the Sanford Underground Research Facility in South Dakota. It's scheduled to begin operation in 2026.

I am a member of the Data Aquisition System (DAQ) consortium, where I lead the Control, Configuration and Monitoring group.


With colleagues I founded the interdisciplinary Centre for High-Throughput Digital Electronics and Machine Learning and I am a member of the FastML Scientific committee.


DUNE Collaboration, Fermi National Accelerator Laboratory, 2018

CMS Collaboration, Centre Europeen de Recherche Nucleaire, CERN, 2006

ZEUS Collaboration, Deutsches Elektronen-Synchroton, DESY, 1998 - 2006

Research Staff





Research Student Supervision

Baber,M, Search for supersymmetry in the first √s = 13 TeV pp-collisions using the αT variable with the CMS detector

Brown,C, The High-Luminosity Upgrade of the CMS Detector

Elwood,A, A search for supersymmetry in sqrt(s)=13 TeV proton-proton collisions with the CMS detector at the LHC

Law,KH, Search for new physics through Hidden Valley dark showers in b-quark decays

Lucas,R, Searches for Supersymmetry with compressed mass spectra using monojet events with the CMS detector at the LHC

Marrouche,J, Triggering and W-Polarisation Studies with CMS at the LHC

Mathias,B, Search for supersymmetry in pp collisions with all-hadronic final states using the αT variable with the CMS detector at the LHC

Milošević,V, Search for invisible decays of the Higgs boson at √s = 13 TeV

Ourida,T, Applications of FPGA accelerated machine learning to particle physics

Shtipliyski,A, Systems and algorithms for low-latency event reconstruction for upgrades of the level-1 trigger of the CMS experiment at CERN

Sparrow,A, Measurement of the Polarisation of the W Boson and Application to Supersymmetry Searches at the Large Hadron Collider

Summers,S, Application of FPGAs to Triggering in High Energy Physics

Våge,LH, Acceleration of trigger algorithms with FPGAs at the LHC implemented using higher-level programming languages

Čepaitis,V, Flavour-universal search for heavy neutral leptons with a deep neural network-based displaced jet tagger with the CMS experiment