Priscilla Brooks Cushman
Professor of Physics
University of Minnesota
Current Experiments:
Cryogenic Dark Matter Search
CDMS The Universe is composed of
stuff we see (stars, galaxies, gas clouds) and stuff we don't. Gravitational studies of
the motions of the stuff we see indicates that it only makes up about 4% of what's out
there. The rest is dark energy and dark matter. The dark matter could be particles created at the Big Bang which are still around today. Although there is indirect astrophysical evidence for dark matter, we hope to capture individual dark matter particles in our germanium detectors. The small signals generated by such interactions can only be detected by shielding ourselves from normal cosmic rays (go deep underground) and by reducing thermal interactions (we run at 0.05 degrees above absolute zero, colder than interstellar space!). CDMS is installed in the Soudan Mine
in Northern Minnesota and has been setting the most sensitive limits on the number of dark matter particles in our galaxy for the last 9 years.
The final data set using our regular detectors will be released by December 18, 2009. Improved Germanium detectors are installed and are running now in an experiment called SuperCDMS. Eventually they will be moved to a deeper site in Canada, called SNOLab. My talk at CIPANP 2009 Searching for Dark Matter in the Cosmos and Underground is an overview of both indirect and direct Dark Matter Searches worldwide.
Our research group at Minnesota
Short review article on Dark Matter Detection
Report on CDMS for the TAUP05 Conference
For a more visual representation (and musical!) of the CDMS detector, try my YouTube Video or download a better quality file here
An interesting animation of the CDMS shielding and detector created by an undergrad at Case Western.
Compact Muon Solenoid Collaboration (At CERN, Geneva, Switzerland),
CMS If the zoo of elementary particles is larger than we expect, there may be supersymmetric particles with masses just beyond what has been possible to make in colliders up to now. The new Large Hadron Collider (LHC) at CERN had a bit of a hiccup (understatement) when it tried to turn on in 2008, but all lights are green for a December 2009 start-up. With its higher center of mass energy, it will create new particles and the CMS experiment will detect them. Indeed, some of the new particles may be the dark matter particles we are looking for in the CDMS experiment. Minnesota is responsible for more than 10,000 channels of
new hybrid photodiode readout installed in the hadronic calorimeter (HCAL) of the CMS experiment now at CERN. If you want to find out more about them,
you can view a recent talk at IEEE symposium IEEE symposium
or download the conference proceeding paper
Deep Underground Science and Engineering Laboratory or DUSEL at the Homestake Mine in South Dakota: DUSEL Website. This would be a premier US laboratory dedicated to Underground Physics as well as biology, geology, rock engineering, etc. The NSF has started a design process for the lab, hoping to secure MREFC funding by 2011. I am PI of AARM (Assay and Acquisition of RadioPure Materials) which is designing the facility within DUSEL that will characterize background radiation in both the cavern itself and in materials that will be used for shielding and experimental fabrication. Ultra-sensitive screening detectors and ultra-pure materials have become a major factor in the success of experiments that search for very rare events. You can see a presentation of our preliminary design work AARM Slides from Oct 2009 DUSEL meeting and read a more general paper from the NSF Deep Science Report Low Level Counting.
Past Experiments:
The Brookhaven Muon g-2 Experiment
BNL g-2
to determine the
anomalous magnetic moment of the muon finished several years ago.
In February 2001, we announced a 2.6 sigma discrepancy with the
Standard Model. Read about it! We continued to improve our experimental precision with our latest result . A discrepancy with the Standard Model simply means that unknown particles or fields are affecting the precession of the magnetic moment of the muon. It could be the first evidence for supersymmetric particles. If so, how would that fit in with the dark matter question? See Muon g-2 Constraints to SUSY Dark Matter over the Next Decade for those connections.
For more detail about the experiment, you can see a talk I gave at Fermilab here. We are still dealing with a hint of a discrepancy with the standard model, but the theory numbers still need to settle down. A new g-2 experiment is proposed for Fermilab in the next decade, so Stay Tuned.
Brookhaven E952:
The NuMass Experiment
to make a direct measurement of the
muon neutrino mass using the g-2 storage ring.
Some historical plots
relating to the status of the muon neutrino mass:
Past Experiments and how
much better the
BNL experiment limit
will be.
The NuMass Presentation before the BNL PAC:
Power Point version (original)
or pdf file
(some loss of graphic info) Unfortunately, this approved experiment was a casualty of funding cuts. It may be worth resurrecting a version of it for the new Fermilab g-2 experiment when that comes on line.
I am currently on Sabbatical at CERN. Email is best.
Home phone in France: 001 (33)450-77-3712 (7 hours later than Central Time)
Skype also works well: my contact name is Prisca.Cushman
