Steve Ahlen

Steve Ahlen

Office: PRB, Room 275. 617-353-8940

Office Hours: Mondays, 10 AM - 12 PM and 1:30 PM - 6 PM in SCI 132


Research Interests:

Interactions of Particles and Matter.

My primary focus is on the interactions of particles with matter. I have developed and built magnetic spectrometers for cosmic ray physics above the atmosphere, and he designed and built precision muon tracking detectors for ATLAS, which played an important role in the discovery of the Higgs boson. In addition, I have recently joined the Dark Energy Spectroscopic Instrument collaboration (DESI), where I am working on the construction of the focal plane instrument. Among other things, this will enable the measurement of the expansion rate of the universe over the past 10 billion years, with the goal of distinguishing various models of dark energy. I am currently directing two BU graduate students on DESI, who are working on simulations and analysis of data involving the Lyman alpha forest, and on protoDESI, a prototype detector that will be mounted on the Mayall telescope in the summer of 2016.

Selected Publications:

“Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC,” ATLAS Collaboration, Physics Letters B 716, 1 (2012).

“Atmospheric Neutrino Flux Measurement Using Upgoing Muons,” S. Ahlen et al. (MACRO Collaboration), Phys. Lett. B 357, 481 (1995).

“An Antimatter Spectrometer in Space,” S.P. Ahlen et al. (AMS Collaboration), Nucl. Instr. and Meth. in Physics Research A350, 351 (1994).

“A New Limit on the Low Energy Antiproton/Proton Ratio in the Galactic Cosmic Radiation,” S.P. Ahlen et al. (PBAR Collaboration), Phys. Rev. Lett. 61, 145 (1988).

“Limits on Cold Dark Matter Candidates from the Ultralow Background Germanium Spectrometer,” S.P. Ahlen, F.T. Avignone, R. Brodzinsky, A.K. Drukier, G. Gelmini and D.N. Spergel, Phys. Lett. 195B, 603 (1987).

For a full list of publications, please see the attached CV.


  • Ph.D. - University of California at Berkeley 1976
  • BS, MS - University of Illinois at Chicago 1970, 1971


  • Alfred P. Sloan Research Fellowship

In the news:

Research Descriptions:

The ATLAS Experiment at CERN


The ATLAS experiment is a large detector system developed by a collaboration of physicists from around the world to study very-high-energy proton-proton interactions at the Large Hadron Collider (LHC) at CERN, a laboratory for high energy physics near Geneva, Switzerland. This experiment will probe the origins of electroweak symmetry breaking and the particles associated with the new physics (such as the hypothetical Higgs Boson) that must appear at energies at the symmetry breaking scale. Boston University personnel were involved in the construction and installation of the muon detectors for ATLAS. The detectors occupy a region the size of a five-story building and will measure the trajectories of muons in a magnetic field with a precision of better than 1/10 of a millimeter. This permits the determination of the muon momentum, which will be an important ingredient in searches for new phenomena at the LHC's energy scale, which will be an order of magnitude greater than currently available. Boston University also played a leading role in the development of computing and analysis tools that have been crucial since the experiment's inception. It is expected that many important discoveries in particle physics will be made at the LHC in the coming decade. These discoveries will improve our understanding of the fundamental particles and their interactions, and also of the nature of the early universe. One important goal of the LHC is to search for particles that may be responsible for the so-called "dark matter" of the universe. Possible candidates for this mysterious phenomenon are the particles associated with supersymmetry theories.