SLAC Today is
available online at:
http://today.slac.stanford.edu
In this issue:
Groovy Project Solving Cloudy Problem
Science Today: Taking SUSY
One Step Further
National Research Council Recommends Moving Ahead with NASA-DOE Project
Thursday - September 6, 2007 |
Groovy Project Solving Cloudy ProblemExperiments in the PEP-II accelerator have shown that beam pipes with grooves can snare unwelcome electrons, greatly reducing the formation of electron clouds that can disturb the beam. While electron clouds presently pose little threat to the PEP-II beam, they are a major concern for the International Linear Collider (ILC) or a future B-factory project. In high-energy storage rings, synchrotron radiation liberates electrons from the beam pipe walls. A positron or proton beam will accelerate the free electrons, and these electrons can then strike the chamber walls, releasing more electrons in a cascade effect until a cloud forms. Ultimately, scientists think the grooved chambers will be a good solution for certain sections of the ILC positron damping ring. While PEP-II continued to provide beams for the BaBar experiment this summer, the ILC Group monitored the performance of four segments of beam pipe installed in a straight section of the accelerator where there are no magnets. Two sections have smooth interior walls, like normal beam pipes. Two sections have grooves cut into the interior walls that look like metal teeth on a comb. Data show that the beam pipes with grooves had 20 to 30 times less current from electron clouds than the two smooth segments. The grooves, or teeth, act as traps. Read more... |
||
Taking SUSY
|
National Research Council Recommends Moving Ahead with NASA–DOE ProjectA National Research Council report released yesterday recommends that, of five possible Beyond Einstein missions, NASA should proceed immediately with the Joint Dark Energy Mission (JDEM), a partnership between NASA and the Department of Energy. Late last year, NASA initiated the study of three mission concepts for JDEM: the SuperNova/Acceleration Probe (SNAP), the Advanced Dark Energy Physics Telescope (ADEPT), and the Dark Energy Space Telescope (Destiny). The JDEM mission that actually flies will be determined by a future, open competition. SLAC is currently working in collaboration with several institutions on SNAP, which is designed to reveal the nature of dark energy by measuring the light from thousands of distant supernovae and observing the subtle effects of weak gravitational lensing. Work at SLAC focuses on the probe's electronics and its fine guidance control system. Kavli Institute for Particle Astrophysics and Cosmology researchers are also studying how the probe's strong lens survey will further examine the Hubble constant, put independent constraints on cosmology and dark matter, and study galaxy evolution. "SLAC has been working on this project for several years now," said Aaron Roodman, head of the SLAC SNAP group. "SNAP is a strong JDEM contender and we look forward to the NASA–DOE competition for this mission." The executive summary of the National Research Council Report, NASA's Beyond Einstein Program: An Architecture for Implementation, is available online. In addition to recommending that JDEM proceed immediately, the report recommends that NASA should invest additional Beyond Einstein funds in technology, development and risk reduction for the Laser Interferometer Space Antenna (LISA), and should increase the readiness of the three remaining dark energy mission areas—Black Hole Finder Probe, Constellation-X, and Inflation Probe. All five of these missions are part of the Beyond Einstein Program, NASA's research roadmap for proposed mission areas to study the most compelling questions arising at the intersection of physics and astronomy. Read the National Academies press release... Read the Lawrence Berkeley National Laboratory press release... |
Events (see all | submit)
Access (see all)
Announcements
|
| ||
<%
Response.AddHeader "Last-modified", getArticleDate()
'Response.AddHeader "Last-modified","Mon, 01 Sep 1997 01:03:33 GMT"
'Monday, December 06, 2010
%> View online at http://today.slac.stanford.edu/. |