Overview Week - ATLAS looks forward to having beams!
Lyn Evans, head of the LHC project at CERN, brought very good news: all problems are now solved or understood, and barring a disaster, the LHC should see beams in July 2008.
The ATLAS overview week (8-12 October) showed impressively that the experiment is getting ready for beams on all fronts. Perhaps that is best seen in the recent runs with cosmic events, which are integrating all ATLAS subsystems. The integration milestone M4 ended just a month ago (see the article in the September issue of ATLAS e-news), exercising for one week the complete chain from detectors - trigger and data acquisition - reconstruction at Tier0 - shipment of data worldwide to Tier1s. Event displays and histograms, available both online and offline, were shown throughout the overview week and are proof that the entire chain is actually working. The integration milestones give an enormous boost to the experiment - next time during M5 end of October.
During the week we learned about successes and remaining issues along this entire chain. But maybe most importantly, we also received the latest status of the LHC machine itself. The two messages are: the problem with the inner triplet magnets are now resolved; and the more recent problem with the so-called plugin modules which shim the vacuum bellows from the electromagnetic fields of the bunches, will not cause delays. This thanks to a diagnostic device traveling through the beam pipe, identifying the few places which really need repair. So assuming no new problems arise in the machine, be prepared for first collisions next July! One can call this a success oriented schedule, and it is that type of schedule which works well in ATLAS installation and commissioning.
As usual, Peter Jenni's introductory talk was very well attended.
The integration of the offline, high-level trigger, and data acquisition software made a big leap forward - it now takes just a few days until a fresh offline release can be used at Point 1. The wheelwork of offline computing operations is getting up to speed. More and more users get exposed to the Grid in distributed analysis and provide useful feedback to debug and optimize the system. The physics studies and strategies session this time covered Di-Boson physics, measurement of the top mass, Higgs via Vector Boson Fusion, and search for Black Holes in early data. The analysis strategy will be prepared for the unknown territory opened by LHC. Sure enough, for the worldwide collaboration to function well, the conferencing tools will need to work as nicely as the session recording already does. Have a look at Steve Goldfarb's article in this issue.
Here are some statistics for the overview sessions: full audience during the first and last half days, and during the LHC presentation; half to quarter full during the other sessions. Only some 20 mobile phone rings during the week - and only every seventh participant sitting in front of an open laptop.
Hans von der Schmitt
Max-Planck-Institut fuer Physik
Forward Detectors -A new sub-detector for ATLAS
Since last August, the ATLAS detector family has been joined by a new little member named LUCID, from the acronym "LUminosity Cerenkov Integrating Detector". This may well surprise you if you are already aware that LUCID construction started only in February after its approval by an ATLAS-management mandated review committee. The rapid progress from approval to installation is the result of the close collaboration between groups from Alberta (Canada), INFN Bologna (Italy), Lund (Sweden) and CERN. LUCID is primarily intended to measure the luminosity delivered by the LHC to ATLAS with a systematic uncertainty in the range of a few percent. To achieve such a precision and still meet the demanding installation schedule, the LUCID developers prized simplicity and robustness above all.
One of the LUCID vessels while under construction. One can see the aluminum Cerenkov tubes and the photomultiplier mount (plugged into the upper flange).
The two fully assembled LUCID vessels seen from the front end electronics side with their readout photomultiplier tubes.
The LUCID Monte Carlo simulation shows that the luminosity is proportional to the number of hit tubes i.e. the number of tubes for which the detected Cerenkov light is above a preset threshold.
The detector design was inspired by CDF's luminosity monitor, the CLC and calls for two identical arms, placed symmetrically at about 17 m from the ATLAS interaction point. Each arm is made of 20 tubes, each one being contained in a cylindrical aluminum vessel filled with radiator gas of low refractive index. When fast charged particles, for example electrons with momenta above 10 MeV or pions with at least 2.8 GeV go through the radiator, Cerenkov light is emitted. The light produced in each tube is proportional to the number of tracks originating from the interaction point which cross it and, therefore, to the luminosity produced at the ATLAS interaction point, as can be seen on the plot shown above. The light is focused by Winston cones and measured by photomultipliers (PMT). For sixteen of the 20 tubes of each arm, the readout PMTs are coupled directly to their radiator tubes, while for the remaining four, the Cerenkov light is transmitted via quartz fibers, a few meters in length to multi-anode PMTs. This latter scheme has the disadvantage of less signal (due to attenuation in the fibers), but the advantage of allowing the PMTs to be moved into a lower radiation environment. Doing so is not strictly necessary even at full LHC design luminosity, however it affords an opportunity to test a possible solution for the ten-times higher luminosity of the LHC. The detector and associated readout will be sufficiently precise in time to allow the luminosity measurement of each individual LHC bunch crossing and will thus provide, online, a very important monitor of beam conditions. Last, but not least, thanks to its high-speed signal processing electronics, LUCID could also provide an interaction trigger for ATLAS during low luminosity (less than 1 interaction per bunch crossing) runs.
For an absolute luminosity measurement, LUCID must be calibrated. The calibration is planned to proceed in steps of successively higher accuracy. During the initial running, the calibration will rely on calculations based on the LHC machine parameters. It will soon become possible to use physics processes instead, such as W and Z counting and exclusive muon pair production via two photon interactions. Ultimately, the most accurate calibration will come from the ALFA Roman-pot detectors which will measure elastic scattering in the Coulomb interference region. With this final calibration, LUCID will measure the luminosity with an accuracy of better than 5% . The robust design and fast processing electronics of LUCID could allow its employment for other purposes, for example as a beam loss monitor which would (together with the ATLAS Beam Condition Monitor) trigger a fast beam dump when dangerously high radiation levels are detected (under study).
Marco Bruschi
Universita & INFN, Bologna
Web Lectures -Recent recordings
The University of Michigan ATLAS Collaboratory Project is happy to announce the publication of a number of recent web lectures, including the full Plenary Session from the ATLAS Overview Week, held at CERN in October. Archives from that event are located here and directly on the Indico agenda.
Click on the pictures below to access more information.
Latest News
As announced in the Collaborative Tool Workshop, held on Tuesday of the Overview Week, future events in the Michigan Archives will be available for viewing with a Flash Player plug-in (right image above), as well as the usual Real Player plug-in. This additional option, made possible by our usage of the Lecture Object and standard formats for storing all media and metadata, allows the viewer to choose her/his preferred environment. As always, viewing of the lectures is supported on all major platforms and browsers and there is also the option to download lectures for remote viewing with limited or no network bandwidth.
ATLAS 2007 Archives
Additional ATLAS material for 2007, including plenary lectures, workshops and tutorials, can be found via our portal at http://www.wlap.org/atlas including:
Suggestions for events or tutorials to record in 2007, as well as feedback on existing archives is always welcome. Please contact us at wlap@umich.edu. Thank you.
Enjoy the Lectures!
The Michigan Web Lecture Team
Tushar Bhatnagar,
Steven Goldfarb,
Jeremy Herr,
Curtis Hiller,
Mitch McLachlan,
Homer A. Neal
Steven Goldfarb
University of Michigan
Gender and Equity Issues -The new childcare initiative
The ATLAS Women's Network recently sent out a general mailing to all ATLAS and CMS members to announce a new initiative aimed at improving childcare facilities for Users coming to CERN. Several people have expressed the need that CERN should provide or facilitate affordable day care for children of temporary visitors at CERN. The ATLAS Women's Network is now forming a child care task force from concerned people and invites all those interested to join this effort. You can do so by either adding your name to the mailing list cern-users-childcare@cern.ch in Simba or by contacting Cigdem.Issever@cern.NOSPAM.ch and Pauline.Gagnon@cern.NOSPAM.ch. More than 50 people have already joined this effort. Those who have joined the mailing list will soon receive all the details about the next conference call meeting which has been scheduled for Thursday October 25th from 16:30 to 18:00 CERN time. The preliminary agenda is the following:
Summary of our first contact of ATLAS and CMS (5 min)
Discussion about the co-convenor. (10 min)
Experience of a User with her own initiative to improve childcare at CERN. (15 min)
Discussion about a questionnaire about assessing child care needs at CERN. (20 min)
The steps we intend to take are:
Make an assessment of the needs and existing resources.
Make a formal presentation to the Advisory Committee of CERN Users (ACCU ) and ask for their support.
Work jointly with ACCU to find solutions.
Parents have to be pretty creative when they come to work at CERN for a short period.
We ought to find better solutions for people with young children coming for short visits at CERN.
At least, ATLAS provides a few distractions for kids in building 40.
Cigdem Issever -
Oxford University
Pauline Gagnon -
Indiana University
Photo Gallery -Best pictures of the month
The last sector of the Big Muon Wheels was brought to the cavern in the morning of September 20...
... installed on one of the Big Muon Wheels during the same afternoon...
... just in time to sqeeze lots of people in between two of the all-completed Big Muon Wheels on the 21st of September to celebrate the installation of the last sector.
Installation of the first ATLAS small wheel in building 191 on September 10.
Some of the people involved in the construction and installation of the chambers on the first ATLAS small wheel in building 191 celebrating its completion on September 20.
After hearing that the rock band The Police played in Geneva last month, Muriel got inspired and decided to become a rock star, just like one of her favorites, Keith Richards from the Rolling Stones.
Special accomplishment of the month: (top) Martina Hurwitz (#908) and Monica Dunford (680), both from the Chicago University group, completed the Lausanne Marathon on October 21 in 4h 49m 22.3s and 4h 34m 44.8s, respectively. (bottom) Twice the age, half the distance: Pauline Gagnon (#4108), from Indiana University, ran the half marathon the same day in 2h 9m 44.5s. All are still happily recovering.
Claudia Marcelloni de Oliveira -
Laurence Berkeley National Lab.
Pauline Gagnon -
Indiana University
Miscellaneous -Particle physics and the anthropology of right and left
We have all looked at ants at some point and wondered where they go about with so much dash and drive. Likewise I ask what drives so many competent and specialized people in this gigantic collaborative enterprise on the LHC at CERN. And I come at an interesting cross-section that is in a process to change soon with the LHC assuming operation from April 2008. But I am also here to learn something about physics. The metaphor of the ant is useful in describing my particular focus of interest: there is no reason why an ant should take one direction, rather than the other; the ant can select any direction. In an otherwise homogeneous space, what does right and left mean ? The distinction between right and left is not embedded in space itself, it is relative to each other and cannot be made unless the perspective from which it could be viewed is specified. Making this distinction of right and left is then a matter of social convention or custom.
Physicists, philosophers, anthropologists alike have wondered why nature should treat left- and right-handed varieties of certain processes differently. Why I should not be able to wear my left shoe on my right foot, given that the feet are exactly similar, is indeed a puzzle. I am interested in this concept of handedness and the role it plays in particle physics. By focusing on the specific case of parity or handedness, I wish to arrive at an anthropological understanding of how particles are (a) given identity relative to norms of handedness, (b) are arranged into system of classification; and (c) become part of cosmological narratives, ranging from the origin of mass to the origin of the universe. My work is not a simple description of how science is done, or a prescription for a better science, but a look at the fundamental presuppositions on which it is based. There are forms of systematic thoughts in the world, even as rigorous as physics, which cannot see their own boundaries. Anthropological methods are often useful in highlighting the presuppositions that inform scientific outcomes and illustrating the ways in which scientific truth is discursive or symbolic. By focusing on the specific concept of handedness in the world of elementary particles, I aim to understand how social custom or convention enters the objective world of physics.
I am an anthropologist and my research involves talking to you people, understanding your work, what are the risks you face, what are the stakes of your job, etc. I understand that you are busy but if you have time to spare for a coffee or have something interesting to tell, I will listen. As I collect information, I will have a richer understanding of the processes that will accomplish the successful running of the LHC experiments.
A new face that will be seen around ATLAS often in the coming months. Arpita Roy, a graduate student in Anthropology from University of California in Berkeley.
Arpita Roy
University of California in Berkeley
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Miscellaneous - Remote video conferencing teaching from CERN
For those of us who are teaching at a university, coming to CERN for a week means that someone else has to be found to teach our course. Recently, thanks to an initiative of CERN's Education Group who in collaboration with the IT department have buit a Remote Video Conference (VC) room for outreach communication with schools, I have been able to test teaching class back home whilst at the same time being at CERN!
On Monday October 5, at 16:00, (10:00 at Indiana University), I attempted my first remote class. Of course, I could not do this alone. Back in the main auditorium in the physics Department, Hal Evans and Fred Luehring had rolled in a portable teleconference center, set up lecture demos and started a class computer. At CERN, Knut Bjorkli had the teaching center teleconference screen active, and had also connected to my class website when I arrived. The first day startup was a bit rocky - there were fire wall problems (?) that required that we connect to the Indiana VC unit rather than the other way around, and the sound systems took a bit of adjustment, but after the first five minutes, the class proceeded well.
A live but still lively lecture broadcasted from CERN for an audience sitting in Bloomington, Indiana, USA.
I am teaching an introductory class for non-science majors called Cellphone 101 with an enrollment of 180. I hope that it is a way to reduce the mystery of how mobile phones (and other electronic gadgets) operate, and along the way introduce the students to the physics of waves- sound, radio, and light. The ?textbook? is a wiki set of chapters that links to online sources, reviews concepts and summarizes material. It is this wiki page that I screen-shared with the computer at IU during my VC lecture. It was displayed on a large central video projector screen. The mobile VC unit handled my voice, and displayed my image on a second screen in class.
A packed classroom at Indiana University getting an oversea lecture from Harold Ogren at CERN.
Wednesday and Friday at 16:00 CERN time classes also went very smoothly. The VC unit connection was now understood, the screen sharing was easy, and I was able to proceed with my lecture notes very much as though I was right in the class. Hal Evans did and in-class demonstration of relflection and absorbtion of microwaves.
However, since I was at CERN, I started all the sessions with some of the images and videos about CERN and the ATLAS detector. This generated lots of questions, especially for the first two days. I think my students have a much better idea of CERN and the ATLAS experiment. The video conferencing serves as both a teaching resource for those of us who need to travel to CERN as well as an outreach activity.
The University of Michigan ATLAS Collaboratory Project, under the direction of Homer Neal, is conducting a pilot run during the academic year 2006-2007 to assess how useful this remote teaching capability might be. The Education Group VC facility is primarily intended for outreach communication with schools but requests to test remote teaching will be considered - please contact mick.storr@cernNOSPAM.ch. If further tests prove to be positive then it is hoped that the ATLAS management and the IT department will consider providing a dedicated remote video conference teaching facility.
