Richard Gaitskell

Associate Professor:
Physics
Phone: +1 401 863 9783
Phone 2: +1 401 996 3799
Richard_Gaitskell@brown.edu

Professor Gaitskell leads a research team hunting for direct evidence of particle dark matter, one of physics' greatest unclaimed prizes. His group is working on experiments that have detectors located in underground laboratories in the Soudan Mine, Minnesota, (CDMS Experiment) and at the Gran Sasso Underground Laboratory, Italy (XENON Experiment). The CDMS experiment which has been operating for 5 years is the worlds most sensitive dark matter detector. XENON has recently started operation.

Biography

Prof. Gaitskell joined the Brown faculty in 2001. He is the head of the Particle Astrophysics Group which is part of the Cosmology and Astrophysics Program at Brown. The Particle Astrophysics Group is currently collaborating on the CDMS II (Cryogenic Dark Matter Search) and XENON Experiments which are searching for the direct interaction of Particle Dark Matter in deep underground laboratories. Prior to coming to Brown, Prof. Gaitskell held positions as a Faculty Senior Lecturer in the Department of Physics and Astronomy, University College London, UK; he was a Fellow at the Center for Particle Astrophysics in UC Berkeley, CA; a Visiting Scholar at Stanford University, CA; and a Prize Fellow at Magdalen College, Oxford, also working at Dept. of Physics, Oxford University, UK. His thesis (in dark matter detection) and undergraduate BSc/MA degree are from Oxford University, UK.

Research Description

For further details of our research please see http://particleastro.brown.edu

A wealth of observations, dating back 70 years [1], show that the universe is composed of >96% invisible matter and energy [see 2, and refs. therein]. The nature of these missing components is one of the most fundamental questions in physics, and has attracted broad attention from the public. The leading candidate for the invisible "dark matter" is subatomic particles left over from the big bang known as Weakly Interacting Massive Particles (WIMPs). Such particles are also predicted by supersymmetry, a favored class of new particle models [3]. If WIMPs exist, they are also the dominant mass in our own Milky Way, and, though they only very rarely interact with conventional matter, should nonetheless be detectable by sufficiently sensitive detectors on Earth. The primary challenge in detecting them is reducing natural radioactivity. If no effort is made to reduce this background radioactivity, it would mask the dark matter signal by some 10 or more, orders of magnitude. The primary techniques for reducing this radioactive background are placing detectors in a suitable deep underground location, of which there are only a handful worldwide, and using a sophisticated shield against ambient radioactivity from the rock and cavern infrastructure.

Gaitskell's group is actively involved in the development and operation of detectors that are capable of detecting dark matter particle interactions. The current main focus is on a detector based around liquid xenon (LXe). When a particle interaction occurs in LXe both scintillation light and ionization (electron-ion) signals are created. These signals can be detected using arrays of photomultipliers (PMTs). The XENON10 experiment, which recently began operation in the Gran Sasso Underground Laboratory, Italy, has a 22 kg LXe target observed by some 90 PMTs.

The research group continues to work on alternative photodetection techniques to replace PMTs, in order to provide better quantum efficiency for the light detection, and lower intrinsic radioactivity.

Gaitskell has had extensive experience of dark matter deployment and operation at underground labs being a PI on both the CDMS II (Soudan, MN), which he is now winding down his involvement on, and the XENON (Gran Sasso, Italy) experiments, which he is actively involved in. He has also constructed and operated a low background gamma screening facility (SOLO) at the Soudan Mine.

References

[1] F. Zwicky, Helv. Phys. Acta, 6 (1933), 110.

[2] R. J. Gaitskell, Ann. Rev. Nucl. Part. Sci. 54 (2004) 315.

[3] W. Freedman and M Turner, Rev. Mod. Phys. 75 (2003) 1433.; C. Munoz, Int. J. Mod. Phys. A19 (2004) 3093.; J. Feng, hep-ph/0405215 (2004).

[4] E. Aprile et al., "The XENON Dark Matter Search Experiment", Proc. of the 6th UCLA Symposium on Sources and Detection of Dark Matter, Santa Monica Feb 2004, astro-ph/0407575

[5] D.S. Akerib et al. (CDMS Collaboration), "Limits on spin-dependent WIMP-nucleon interactions from the Cryogenic Dark Matter Search", Phys. Rev. D73 (2006) 011102, astro-ph/0509269; D.S. Akerib et al. (CDMS Collaboration), "Limits on spin-independent WIMP-nucleon interactions from the two-tower run of the Cryogenic Dark Matter Search", Phys. Rev. Lett. 96 (2006) 011302, astro-ph/0509259; D. S. Akerib, et al. (CDMS Collaboration), "Exclusion Limits on the WIMP-Nucleon Cross-Section from the First Run of the Cryogenic Dark Matter Search in the Soudan Underground Lab", Phys. Rev. D72 (2005) 052009, astro-ph/0507190.

[6] E. Aprile et al., Simultaneous Measurement of Ionization and Scintillation from Nuclear Recoils in Liquid Xenon as Target for a Dark Matter Experiment, submitted to Phys. Rev. Lett. (Dec 2005) (astro-ph/0601552)

Honors and Awards

2003- Outstanding Junior Investigator, Department of Energy, High Energy Physics

1995-00 Center Fellowship, Center for Particle Astrophysics, UC Berkeley, 301 LeConte Hall, Berkeley, CA 94720, USA

1995 Lindemann Fellowship, The Lindemann Trust Committee, Dartmouth House, 37 Charles Street, London W1X 8AB, UK (stipend not taken up)

1993-95 Fellowship by Examination, Magdalen College, Oxford, OX1 4AU, UK

1993-95 Post Doctoral Research Fellowship, PPARC (Particle Physics and Astronomy Research Council) Polaris House, North Star Avenue, Swindon, Wilts SN2 1SZ, UK

1993 D.Phil. in Physics, St John's College, Oxford University, UK

1989 Graduate Studentship, SERC (Science and Engineering Research Council), UK (address as PPARC above)

1989 Corporate Finance Evening Course Graduate, London Business School, London, UK

1987 Qualified Registered Representative, London Stock Exchange, London, UK

1985 BA Hons. Degree in Physics, St John's College, Oxford University, UK 2nd(1)

1981 Open Scholarship, St John's College, Oxford University, UK

1981 Scholarship, Worshipful Company of Scientific Instrument Makers, London, UK

Affiliations

None

Teaching Experience

In Spring 2005 I taught PH0008 (Quantum Mechanics and Special Relativity, class size 65) for the 4th time. This class is aimed at the strongest students scientifically and mathematically, many of whom will be considering concentrating in Physics, or other sciences. However, the class also includes students who are looking for greater insights into two of the key developments in early 20th century physics. It is a class where common sense is no longer a reliable guide. Students are required to apply mathematics, and the scientific method, in order to interpret the many puzzling experimental results from this period. It is my aim that the students can experience the revolution in thinking that was necessary in order to create new physics frameworks to understand the experimental results that contradicted the prevailing classical models of the 19th century.

In Fall 2005 I started teaching PH0047 (Electricity and Magnetism, class size 42) for the first time. This is the physics department's main course in Fall semester for sophomores who are continuing to pursue physics at an advanced level and who intend to concentrate in physics, or a related track. This is often the first experience students have with a rigorous (and fairly complete) development of a theoretical framework that is used for detailed quantitative analysis of experimental results. It is an important exercise in building their confidence for taking advanced science classes. For the most part, the style of teaching in this class is a radical departure from the way they have been used to having science taught at High School, given that formulae are not simply given, but are developed from the ground up.

I included a number of innovative teaching techniques for PH8. The full lecture course is prepared and delivered using Powerpoint. A significant amount of prepared material is made available to the students via the WebCT system. I often provide supplementary material on the web to help guide them on the more challenging mathematical derivations at their own pace following the lectures, should they be unable to convince themselves of the validity of every step during the lecture. The lectures include numerous computer generated animations authored by myself to better illustrate some of the physics/mathematical concepts. In addition, video material was edited digitally from a number of sources for direct inclusion in the lecture slides. Full copies of all the lectures are made available to the students before the lectures in order to facilitate note taking. The PRS (personal response system) was also used throughout the lecture series. "PRS" gives each student a 'clicker' with which to respond in real-time to multiple choice questions. The questions can be tailored to clarify specific aspects of the course material, as well as encouraging class interaction/discussion. This is a useful supplement to the feedback I obtain from requesting verbal answers in the class. With a lecture theatre of 50 students it is not possible to elicit oral answers from all students, and the PRS system has provided a useful technology to maintain the same air of challenge/answer. Often, I am able to use rather subtle, or even trick, questions to really make important points on the subject under discussion. For the more common misconceptions, students can be made rapidly aware of why their thinking is incorrect. I am also able to get feedback on the level of comprehension of each teaching block, and review material accordingly. The Powerpoint slides and PRS system were both well received, and their use will be repeated in subsequent courses. I discussed the use of technology in teaching at a workshop organized by the Brown Technology Group in Jan 2005 and found the exchange of ideas with other faculty in the forum very useful.

I adopted a similar teaching strategy with the PH47. The lectures included many computer–generated simulations that I designed to best illustrate the advanced mathematical formulae that are core–content of the course. As in PH8 many experimental demonstrations (facilitated, in a very professional manner, by Jerry Zani) were used to illustrate course concepts. I worked closely with Dean Hudek and the graduate TAs to ensure that the associated laboratory sessions further illustrated the concepts discussed in the lecture.

Funded Research

Prof. Richard Gaitskell, Brown University
(Summary of All Research Support, as of 1/06)
Current: Department Of Energy: XENON10 WIMP Dark Matter Xe Detector Array (plus small component supporting CDMS Dark Matter Search).
SOURCE OF SUPPORT: Department Of Energy
TOTAL AWARD AMOUNT: $392,000
TOTAL AWARD PERIOD: 10/01/05-09/30/06 (part of rolling grant from DOE High Energy Physics)
LOCATION OF PROJECT: Brown University/Nevis Laboratory, Columbia/Gran Sasso Underground Laboratory, Italy
PERSON-MONTHS PER YEAR: (Summer/Academic/Calendar) 2 / 0 / 0

Pending: National Science Foundation MRI Instrument Development Proposal
Development of Low Radioactivity Background Water Shield System at Homestake Mine, South Dakota
SOURCE OF SUPPORT: National Science Foundation
TOTAL AWARD AMOUNT: $713,172
TOTAL AWARD PERIOD: 10/01/06-09/30/07
LOCATION OF PROJECT: Brown University/Homestake Mine, SD
PERSON-MONTHS PER YEAR: (Summer/Academic/Calendar) 0.5 / 0 / 0

Completed

Outstanding Junior Investigator (OJI) Award from Department Of Energy: Development of Advanced Photo Detectors for WIMP Dark Matter Xe Detector Array (DOE) These funds are being used to support my participation in the XENON dark matter project 10/01/03-10/01/05, Rolling grant at a level of $85,000 p.a.

CDMS II Experiment (Department Of Energy) 10/01/04-10/01/05, Rolling grant at a level of $77,000 p.a.

CDMS II Experiment (National Science Foundation) 09/01/01-04/30/02 ~$30,000 Early phase funding at Brown from NSF for CDMS experiment

XENON Proposal (National Science Foundation) 07/01/02-06/30/04 $78,000 Sub-award, single PI

CDMS II Experiment (National Science Foundation) 05/01/02-10/31/03 $102,399 Sub-award

Web Links

Curriculum Vitae

Download Richard Gaitskell's Curriculum Vitae in PDF Format