James Rohlf

James Rohlf

Office: PRB, Room 475. 617-353-6035
Lab: PRB, Room 459. 617-353-5635


Research Interests:

Experimental high energy physics. 

Please see my other BU page: http://physics.bu.edu/~rohlf/

And for an up-to-date list of publications, see inspire

Selected papers:

  • 05/19/11 Search for resonances in the dilepton mass distribution in pp collisions at sqrt(s) =7 TeV
  • 05/18/11 Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at sqrt(s)= 7 TeV
  • 05/17/11 Search for large extra dimensions in the diphoton final state at the Large Hadron Collider
  • 05/17/11 Search for Pair Production of First-Generation Scalar Leptoquarks in pp Collisions at √s=7  TeV
  • 05/17/11 Search for Pair Production of Second-Generation Scalar Leptoquarks in pp Collisions at √s=7  TeV
  • 05/12/11 Strange particle production in pp collisions at sqrt(s) = 0.9 and 7 TeV
  • 05/04/11 Measurement of Bose-Einstein correlations in pp collisions at sqrt(s) = 0.9 and 7 TeV
  • 05/02/11 First Measurement of Hadronic Event Shapes in pp Collisions at sqrt(s)=7 TeV
  • 04/12/11 Measurement of the lepton charge asymmetry in inclusive W production in pp collisions at sqrt(s)=7 TeV.
  • 03/28/11 Measurement of B anti-B Angular Correlations based on Secondary Vertex Reconstruction at sqrt(s)=7 TeV.
  • 03/28/11 Search for a heavy gauge boson W' in the final state with an electron and large missing transverse energy in pp collisions at √s = 7 TeV
  • 03/25/11 Measurement of W+W- Production and Search for the Higgs Boson in pp Collisions at sqrt(s) = 7 TeV
  • 03/22/11 Dijet Azimuthal Decorrelations in pp Collisions at sqrt(s)=7 TeV
  • 03/22/11 Prompt and non-prompt J/psi production in pp collisions at sqrt(s) = 7 TeV
  • 03/21/11 Search for Microscopic Black Hole Signatures at the Large Hadron Collider
  • 03/18/11 Inclusive b-hadron production cross section with muons in pp collisions at sqrt(s) = 7 TeV
  • 03/17/11 Measurement of the B+ Production Cross Section in pp Collisions at sqrt(s)=7 TeV
  • 03/16/11 Search for Supersymmetry in pp Collisions at 7 TeV in Events with Jets and Missing Transverse Energy
  • 03/04/11 Search for Heavy Stable Charged Particles in pp collisions at sqrt(s)=7 TeV.
  • 02/23/11 Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at sqrt(s) = 7 TeV
  • 01/19/11 Charged particle multiplicities in pp interactions at sqrt(s) = 0.9, 2.36, and 7 TeV
  • 01/19/11 Measurements of Inclusive W and Z Cross Sections in pp Collisions at sqrt(s)=7 TeV.
  • 01/17/11 First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at sqrt(s)=7 TeV
  • 01/07/11 Search for Stopped Gluinos in pp collisions at sqrt s = 7 TeV
  • 12/20/10 Development of a MicroTCA carrier Hub for CMS at HL-LHC
  • 12/20/10 Search for Quark Compositeness with the Dijet Centrality Ratio in pp Collisions at sqrt(s)=7 TeV
  • 11/24/10 CMS Tracking Performance Results from early LHC Operation
  • 11/17/10 Search for Dijet Resonances in 7 TeV pp Collisions at CMS
  • 11/06/10 First Measurement of the Underlying Event Activity at the LHC with \sqrt{s} = 0.9 TeV.
  • 09/27/10 Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC
  • 07/13/10 Measurement of Bose-Einstein correlations with first CMS data
  • 07/06/10 Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at sqrt(s) = 7 TeV
  • 02/10/10 Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at (√s) = 0.9 and 2.36 TeV

Other papers:

  • 06/20/77 Observation of the Production of Jets of Particles at High Transverse Momentum and Comparison with Inclusive Single Particle Reactions
  • 08/20/79 Experimental Tests of Quantum Chromodynamics in High-p⊥ Jet Production in 200-GeV/c Hadron-Proton Collisions
  • 07/28/80 Observation of a Fourth Upsilon State in e+ e- Annihilations
  • 11/30/99 Evidence for New Flavor Production at the Upsilon (4S)
  • 03/21/83 Observation of Exclusive Decay Modes of B Flavored Mesons
  • 02/24/83 Experimental Observation of Isolated Large Transverse Energy Electrons with Associated Missing Energy at s**(1/2) = 540-GeV
  • 07/07/83 Experimental Observation of Lepton Pairs of Invariant Mass Around 95-GeV/c**2 at the CERN SPS Collider
  • 01/26/84 Observation of the Muonic Decay of the Charged Intermediate Vector Boson
  • 11/01/84 Observation of Muonic Z0 Decay at the anti-p p Collider.
  • 09/22/84 Further Evidence for Charged Intermediate Vector Bosons at the SPS Collider
  • 09/11/86 Angular Distributions for High Mass Jet Pairs and a Limit on the Energy Scale of Compositeness for Quarks from the CERN p anti-p Collider
  • 03/05/87 Search for B0 anti-B0 Oscillations at the CERN Proton - anti-Proton Collider
  • 02/12/87 Events with Large Missing Transverse Energy at the CERN Collider: W ---> tau-neutrino Decay and Test of tau - mu e Universality at Q**2 = m(w**2)
  • 12/26/91  First observation of the beauty baryon LAMBDA(b) in the decay channel LAMBDA(b) ---> J / psi LAMBDA at the CERN proton - anti-proton collider
  • 04/20/07 CMS technical design report, volume II: Physics performance
  • 08/14/08 The CMS experiment at the CERN LHC
  • 08/23/10 Measurement of the charge ratio of atmospheric muons with the CMS detector


Ph.D. Physics, Caltech (1980)

M.S. Physics, UCLA (1975)

B.A. Physics and B.S. Mathematics, University of Minnesota (1973)


publications: inspire

citations summary

Modern Physics Book

As a graduate student I worked on the first experiment to trigger on hadron jets with a calorimeter, Fermilab E260. My thesis used the model of Field and Feynman to compare our observed jets from hadron collisions to that from electron-positon collisions and made detailed acceptance corrections to arrive at first the measurement of quark-quark scattering cross sections. My thesis is published in Nuclear Physics B171 (1980) 1. Thesis committee:  G. C. Fox (advisor), C. Barnes, R. P. Feynman, R. Gomez

At the Cornell Electron Storage Rings, I worked on the discovery of the Upsilon (4S) resonance and using novel event shape variables developed by Steven Wolfram and my thesis advisor, Geoffrey Fox. i performed particle identification of kaons and charmed mesons to establish the quark decay sequence, b --> c.

At CERN  worked on the discovery of the W and Z bosons and measurement of their properties.

Presently, I am working on the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) which is searching for the origin of electroweak symmetry breaking.




In the news:


Research Descriptions:

The Compact Muon Solenoid


The Compact Muon Solenoid (CMS) is a 14 kiloton detector designed to search for new physics at an unprecedented distance scale of 10-19 m at the CERN Large Hadron Collider (LHC). The detector consists of 220 square meters of silicon pixels and strips (80 million channels) for precision charged particle tracking, 75k lead-tungsten crystals for precision electron and photon measurements, a highly segmented 1000-ton brass hadron-calorimeter plus a quartz-fiber forward calorimeter to measure jets from quark and gluon scattering and energy balance, all surrounded by precision muon chambers embedded in the return yoke of the magnet. Overall, the detector features nearly complete solid-angle coverage and can precisely measure electrons, photons, muons, jets and missing energy over a large range of particle energies. These broad capabilities of the CMS detector allow the exploration of electroweak symmetry breaking and will enable the potential discovery of physics beyond the Standard Model.

The CMS trigger and data acquisition systems are responsible for ensuring that physics-enriched data samples with potentially interesting events are recorded with high efficiency and good quality. The experiment has a two-level trigger system, unlike most other hadron collider experiments that have more traditional three-level systems. The first physical level is hardware-based and is called the “Level-1 Trigger” (L1) while the second physical level is software-based and is called the “High-Level Trigger” (HLT). L1 uses information from the calorimeters and muon detectors and is designed to select, in less than 1 ms, the most interesting events starting from a total input (collision) rate of about 40 MHz. The HLT processor farm further decreases the event rate from around 100 kHz to around 400 Hz, before data storage. The trigger system, therefore, has to provide a high selectivity of ~10-5 with respect to the active LHC bunch crossings while ensuring that the ability to select rare, exotic events is preserved. Boston University is playing a leading role in the coordination of the CMS Trigger effort with Bose serving as the CMS Trigger Coordinator. Group members were involved in the design and commissioning of the CMS HLT and continue to spearhead the effort.  Many of the BU personnel resident at CERN served as HLT on-call experts during the first LHC Run (Avetisyan, Fantasia and Sperka).

The collision rate at the LHC also presents enormous technical challenges on the design of readout electronics due to the intense radiation environment and the high speed at which millions of channels of data must be processed. The Boston University group has a leadership role in calorimeter electronics and related software (Rohlf and Sulak). The group has designed and built the data concentrator, a sophisticated piece of digital electronics based on modern field programmable gate arrays (FPGAs) to read out the hadron calorimeter. Group members have also led the custom design of the 18-channel hybrid photo-diode used to convert scintillation light from the calorimeter into electrical signals. We have also designed the electronics to feed calorimeter signals into the muon trigger to greatly reduce the backgrounds in the online event selection. Members of the BU CMS team have also helped design the two hadronic forward calorimeters which are positioned at either end of the CMS detector, to pick up the myriad particles coming out of the collision region at shallow angles relative to the beam line. Group members also play a key role in the day-to-day operation of the calorimeter.

The Boston University group is also reaping the physics benefits of our investment in detector hardware, trigger and algorithm development. Group members are making significant contributions to physics analyses involving searches for new particles and the hunt for the Higgs Boson. These analyses include (among many others) searches for heavy gauge bosons and exotic WZ resonances.  We are also playing a leading role in the study of diboson production; the latter is critical for increasing the sensitivity of our Higgs searches and thereby help understand the mechanism of electroweak symmetry breaking. Bose has recently served as the co-convener of the Electroweak Diboson group (2011) and the Resonances group within the Beyond Two Generations physics group (2012-2014)