LNS LUNCHTIME
SEMINAR
Tuesdays at NOON, Kolker Room, 26-414
SPRING 2008 Schedule
May 6th - CANCELLED
George Stephans, MIT
"Where are your computers: Challenges and options for hosting large- scale computing at MIT"
Computing is one aspect of physics research which seems to expand without boundaries. Even users of large off-site research labs are finding a steadily increasing need for local computing resources. In fact, many of those same large labs are finding that it is impossible to accommodate all the computing needs of their research programs on-site and are looking to farm out computing to universities. The standard progression of "local" computing is a decent workstation for all group members, then several computers on desks, then a shelf of computers in the back of a lab. The next step is filling a rack (and eventually many racks) with servers but this requires much more serious infrastructure for power, cooling, and network. This talk will survey the current and future plans within MIT for hosting such large scale computing efforts.
February 5th
Chen-Yu Liu, Indiana University
“Hunting for Evidence of Time Reversal Symmetry Breaking: An electric dipole moment search using a paramagnetic insulator”
The physics that generates a permanent electric dipole moment (EDM) in fundamental particles, like electrons, requires breaking of both parity and time reversal symmetries.
While parity violation has been verified in a wide range of experiments, the direct time reversal process seems much rarer. A non-zero result of the electric dipole moment measurement will provide insights into mechanisms that produce T violation, which is believed to link intimately to the physics of CP violation. I will discuss one such EDM searches at Indiana University. This experiment attempts to measure an induced magnetization in a garnet sample polarized by an external electric field.
February 12th
Steve Ahlen, Boston University
"The ATLAS Muon System"
After many years of hard efforts by thousands of scientists and engineers, the LHC and its experiments will begin taking data from particle collisions very soon. This talk will describe the design, constuction and installation (along with a little history) of the ATLAS muon system, the world's largest person-made magnetic spectrometer. Special attention will be given to the Monitored Drift
Tubes, which provide the precision measurements for momentum
determination. Performance characteristics and physics goals will be
presented.
February 19th
Xiaochao Zheng, University of Virginia
"Using electron scattering to study strong and electroweak interactions
at Jefferson Lab"
Since the 1960's, deep inelastic lepton scattering (DIS) has served as
an important tool to study the structure of the nucleon and strong
interactions. Data from unpolarized DIS established the quark model of
the nucleon and the perturbative feature of QCD; and data from
doubly-polarized DIS is the primary source for our knowledge on the
spin structure of the nucleon.
In this talk I will focus on a third type of DIS: measurement of the
parity violation asymmetry using a polarized beam and an unpolarized
target (PVDIS). The physics of PVDIS will be reviewed. The PVDIS
asymmetry can be used to extract the poorly known weak coupling
constant C2q; and it is also sensitive to many exciting hadronic
effects such as charge symmetry violations. Then I will present a
Jefferson Lab 6 GeV PVDIS experiment (E08-011) which was recently
re-approved by the PAC. I will also present some ideas for extending
the PVDIS program to the JLab12 GeV Upgrade.
February 26th
Prof. Cristiano Galbiati, Princeton
"Large TPC with Underground Argon for WIMP Dark Matter Search"
Abstract: I will report on the latest results on argon dark matter searches with the WARP detector at Gran Sasso. I will also report on recent discovery of underground sources of argon depleted in 39Ar.
Liquid argon is an excellent target for scintillation and ionization detectors and has unique features that make it particularly attractive for detection of WIMP dark matter. For background suppression, the scintillation pulse shape and ionization/ scintillation ratio combine to provide the highest discrimination between nuclear recoils and minimum ionizing events in energy- sensitive detectors. The high selectivity for argon recoils should permit a very sensitive WIMP search with the WARP 140 kg liquid argon detector employing atmospheric argon, currently under construction at Laboratori Nazionali del Gran Sasso.
Possible limits to size and sensitivity of argon dark matter detectors come from 39Ar, a radioactive product of cosmic rays that pollutes atmospheric argon at the level of 1~Bq/kg. The recent discovery of underground sources of argon low in 39Ar opens the path to large dark matter detectors with argon targets.
March 4th
Benjamin Monreal, MIT
"Slow counting of slow neutrinos: precision measurements of solar neutrinos and tritium beta decay"
The Sun generates huge numbers of electron-flavor neutrinos, then provides two laboratories for changing the flavors: the Sun itself drives the MSW oscillation effect, and the vacuum between the Sun and the Earth gives the neutrinos space for free oscillations. The Sudbury Neutrino Observatory has played key role in disentangling these phenomena, resulting in measurements of the mass splittings and mixing angles of the neutrino sector. In this talk, I will present
SNO's history and current status, and give a preview of the data analysis from its third and final running period. SNO's oscillation data puts a lower bound on an important cosmology question: what do neutrinos contribute to the mass of the Universe? A measurement, or an upper bound, must come from direct measurements of beta decay kinematics. I will introduce the KATRIN experiment, now under construction, whose goal is to search for an electron neutrino mass greater than 0.23 eV via precision spectrometry of tritium beta decays.
March 11th
Virginia Brown and June Matthews, MIT
"Neutron-Proton Bremsstrahlung at 225 MeV; Experiment and Theory"
The neutron-proton bremsstrahlung process (np → npγ) is known to be sensitive to meson exchange currents in the nucleon-nucleon interaction. The triply differential cross section for this reaction has been measured [1] for the first time at the Los Alamos Neutron Science Center (LANSCE). The data
confirm a 35-year-old prediction [2] of the alteration in magnitude and shape of the photon angular distribution, which arises from the inclusion of
meson-exchange effects.
In this talk, J. L. Matthews will describe the experiment, and V. R. Brown will describe the theory, including new corrections.
References [1] Y. Safkan et al., Phys. Rev. C75, 031001 (2007); e.g. [2]V. R. Brown and J. Franklin, Phys. Rev. C8, 1706 (1973).
March 18th
T. Botto and M. Berheide,
Schlumberger Doll Research
"Nuclear physics underground: applications to the energy industry"
The worldwide oil & gas industry represents one of the most significant and mature areas of application of nuclear science and technologies in the business world.
Classic examples are use of radiation sources, down-hole generators, detectors and instrumentation, and nuclear modeling. Applications range from reservoir characterization to identify possible reserves, to borehole and fluid characterization in both the exploration and production environments.
In this talk we will give a general introduction to the E&P industry with a focus on nuclear technology and related unique challenges. In the second part we will discuss in more detail how these ideas are implemented in a state-of-the-art commercial tool such as EcoScope(*)
March 25th
SPRING BREAK
April 1st
Harmut Sadrozinski, Santa Cruz Institute for Particle Physics
"GLAST: the LAT Instrument and its Science Capabilities"
The Gamma-Ray Large Area Space Telescope GLAST is scheduled for launch on May 16, 2008. As a partnership between NASA, DoE and several international agencies, it provided the opportunity to merge the expertise of the Space and High Energy Physics communities to build an instrument with science capabilities exceeding those of previous missions by large amounts.
The design concept of the Large Area Telescope (LAT) on GLAST will be explained and crucial details of the instrument construction will be described. The anticipated performance will be shown, and how it will influence the planned science program.
April 8th
Tom Walker, MIT
"Measuring Atmospheric Neutrinos at the Sudbury Neutrino Observatory"
Although the Sudbury Neutrino Observatory was designed to observe low-energy neutrinos from the sun, it can also track high-energy muons. While the majority of the observed muons come from cosmic ray showers and travel downward, some are produced by atmospheric neutrino interactions and travel upward.
Because of its great depth and flat overburden, SNO is able to observe muons from a sample of atmospheric neutrinos which have not undergone oscillations
and from a sample that have. I will describe how these data will be used to constrain the flux of atmospheric neutrinos and improve measurements of neutrino mixing parameters.
April 15th
Ilya Kravchenko, MIT
"Preparing for discoveries: computing for LHC physics
and MIT CMS Tier2/CMSAF"
As the LHC startup is approaching, physicists are eagerly awaiting the arrival of the first data. The chance for discoveries is great. How do we find those few hundred Higgs bosons that the Standard Model predicts will be buried in petabytes of data taken in the first year? Will the data and computing resources be available for us to search for striking signs of physics beyond the Standard Model already after the first few days of colliding beams? The MIT Tier2 center provides us with an excellent resource for doing physics in CMS.
I will talk about advantages we have from hosting the Tier2 and from understanding how the CMS computing system works under the hood. The questions of grid computing, distributed storage and high bandwidth networks, that are critical for the tiered CMS computing model to succeed, will be discussed. Finally, I will point out the benefits of the Tier2 project for non-CMS physicists of our Department.
April 22nd
Khaldoun Makhoul, MIT
"Search for Large CP Violation in Bs Decays at the CDF Experiment"
The standard model CKM description of CP violation has been
spectacularly successful in the face of many increasingly precise
measurements from B factories in the B0 and B+ systems.
The search for new physics in CP violation measurements leads us to
the B_s system, where new effects could hide in the phase of B_s
time-evolution amplitudes. I present the first experimental direct
bounds on this phase, using B_s decays collected at the CDF experiment
at the Tevatron.
April 29th
H. Leutwyler, University of Bern
"Recent developments in light flavour hadron physics"
Abstract: One of the fascinating developments in this field is that
lattice methods now start yielding results that concern the low energy
structure of QCD and can be compared with what is known from other
sources. Also, there is considerable progress in understanding the low
energy structure of the Green functions and scattering amplitudes, for
instance regarding the position of the lowest resonance in QCD. On the
other hand, some of the recent experimental results on the decay
Κ → μ ν puzzling, because they amount to a strong violation of the low energy theorem of Callan and Treiman -- taken at face value, these results indicate physics beyond the Standard Model.
May 6th - CANCELLED
George Stephans, MIT
"Where are your computers: Challenges and options for hosting large- scale computing at MIT"
Computing is one aspect of physics research which seems to expand without boundaries. Even users of large off-site research labs are finding a steadily increasing need for local computing resources. In fact, many of those same large labs are finding that it is impossible to accommodate all the computing needs of their research programs on-site and are looking to farm out computing to universities. The standard progression of "local" computing is a decent workstation for all group members, then several computers on desks, then a shelf of computers in the back of a lab. The next step is filling a rack (and eventually many racks) with servers but this requires much more serious infrastructure for power, cooling, and network. This talk will survey the current and future plans within MIT for hosting such large scale computing efforts.
May 13th
Conor Henderson, MIT
"Results of a Global Search for New Physics at the Tevatron"
The Standard Model of particle physics is widely believed to be
incomplete, but as yet there are no clear indications as to what form
the new electroweak scale physics might take.
Rather than focusing on particular new physics scenarios, we present a
new approach where the entire high transverse momentum data collected by
the CDF detector at the Fermilab Tevatron are searched for discrepancies
relative to the Standard Model prediction.
A model-independent approach (Vista) considers the bulk features of the
data, and a quasi-model-independent technique (Sleuth) focuses on the
high-pT tails. Results of this global search for beyond Standard Model
physics will be presented.