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In this issue:
Even Electrons Need a Vacation
Dorfan Today: Luminosity Records
SLUO Statistics Lectures to Begin Tomorrow

SLAC Today

Monday - August 7, 2006

Preparations for SSRL's new beamline 12 will continue during the shutdown.
(Click on image for larger version.)

Even Electrons Need a Vacation

Starting today, SPEAR3 will be shut down for annual maintenance and upgrades. The shutdown, which began this morning at 6:00 a.m. and will last until early October, gives engineers an opportunity to perform maintenance and equipment upgrades.

This year most many of the accelerator upgrades are geared toward implementing top-off injection in SPEAR. Among these upgrades is a new ejection septum chamber, a device located at the point where electrons leave the booster ring to be injected into the SPEAR3 main storage ring. With the present chamber, the beam spreads out slightly as it passes through a special vacuum-tight window, reducing the efficiency of injecting electrons into SPEAR. The new septum chamber will eliminate that problem and give operators a tighter beam out of the booster.  Read more...

(Director's Column - Dorfan Today)


I am now back from the ICHEP conference in Moscow where results from SLAC's high energy physics research made a leading contribution. Throughout my travels I kept a close eye on the performance of the B-Factory from various hotel and conference rooms, and I was delighted to see that PEP-II achieved several major milestones in the past few days. The best seven-day integrated luminosity reached 5385 inverse picobarns (pb-1). This performance has increased over 20% in the past year. Secondly, the total integrated luminosity delivered by PEP-II to BaBar has now exceeded 400 inverse femto-barns (fb-1). Congratulations to the dedicated support staff spread over the Particle and Particle Astrophysics (PPA) and Operations Directorates whose hard work and skill made these achievements possible.

The end of data taking for Run 5 on August 21 will usher in a whole new set of challenges for BaBar and PEP-II. In a carefully choreographed ballet, involving up to 11 shifts per week and spanning the four months until operations resume in early January 2007, BaBar will complete the replacement of the resistive-plate chambers (RPCs) of the barrel muon system with limited-streamer tubes (LST). The first one-third of the new system was installed in Summer 2004 and has performed flawlessly since then, delivering outstanding efficiency for muon detection. Physicists, engineers, and technicians from both SLAC and collaborating BaBar institutions will be working throughout the shutdown to complete the replacement, a task that will greatly benefit from the past year's meticulous planning and preparation.  Read more...

SLUO Statistics Lectures to Begin Tomorrow

The 2006 SLAC Users' Organization Lecture Series on Statistics and Numerical Methods begins tomorrow.

"Statistics issues permeate everything we do, from designing experiments to analyzing the output of the detector," says BaBar physicist Frank Porter of Caltech, who is coordinating the event.

Lectures will be held at the Panofsky Auditorium (not the Kavli Auditorium as earlier scheduled) Tuesdays through Thursdays, August 8-10 and 15-17, and the full week of August 28-September 1. They begin at 10 a.m. and last an hour, with a half-hour scheduled afterward for questions and discussion. This series, the first since 2000, has three themes: confidence intervals, density estimation, and machine learning.

Particle physicist Roger Barlow of the University of Manchester will deliver the first set of talks on classical and Bayesian confidence intervals, a range of values that covers the uncertainty in a measurement. There is a high probability that these topics will yield some especially interesting discussion, says Porter, as there is much contention over which approach has better properties.

In the second week, Porter will cover density estimation, or statements about the probability distributions from which data sets are obtained.

BaBar collaborator Ilya Narsky of Caltech will deliver the third set of lectures. He will cover how to optimize data analysis, including techniques from the world of statisticians that are likely to be new to most high-energy physicists, says Porter.

"We will attempt to educate users about the tools we very much depend on and introduce new ideas for people to think about," says Porter.

The series is free and open to all SLAC users. The 2006 lecture series webpage is available online. For videos of the 2000 lecture series, click here.

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