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Dear friends

Before the final underground integration of the CMS experiment, it is demanded that everything works well. In this aim, various tests are done on the surface; two of them are reported in this issue.

In the middle of July, the Tracker Integration Facility at Meyrin site saw the successful end of the integration test of the forward pixel and strip tracker, as featured in the first article by Mauro Dinardo.

A little bit later, on the other site of CERN, at Prevessin, the H2 beamline was once again witness to a major milestone for CMS. After seven weeks of the activity, a combined run of several subdetectors came to an end, as reported by Anatoli Zarubin in the second article.

However, the work elsewhere on CMS continues as normal; scientists and engineers from all over the world are working hard too. This week sees a spotlight on the Massachusetts Institute of Technology group from Cambridge, Massachusetts (MIT) showing its impact to CMS.

With best wishes,

Dave Barney
Marzena Lapka

Massachusetts Institute of Technology, Cambridge, Massachusetts (USA) in CMS

Members of the MIT CMS Team in front of Buildings 32 at CERN and at MIT.

The Massachusetts Institute of Technology group from Cambridge, Massachusetts brings to CMS the experience of experimental work at most physics laboratories around the world. All together, we have conducted experiments at Fermilab, Brookhaven, SLAC, CERN, DESY, Rutherford and Cornell, deep underground, and even in Antarctica. All seven faculty from MIT and many of the twelve research scientists and postdocs spent significant time at CERN during their formative years.

Our physics interests range from Standard Model Higgs to soft QCD and the physics of hot dense matter in heavy-ion collisions.  Currently we are working on the “1 fb^-1” analyses in the H→WW and H→ττ channels, making sure CMS squeezes every last ounce of potential out of these two channels for the first year’s data taking.  At the same time the heavy-ion crowd is developing CMS as a powerful and competitive heavy-ion detector.

Members of our group were part of CMS from the very beginning, participating in the design and construction of the DAQ system. We continue with DAQ, but have also expanded to work on Tracker operations at the TIF and installation at Cessy, and lead the recently established Data Operations project, which is responsible for getting the Online Data or Monte Carlo processed and distributed to enable users worldwide to carry out their analyses. For heavy-ions, we are developing the algorithms for the High Level Trigger, and finally, at MIT we are operating a Tier-2 center.

Our group’s most important asset is our students. We have nine PhD students learning the tools of trade on CMS, studying the physics of pp and heavy-ion collisions. Traditionally MIT graduate students spend most of their time at the accelerators where they participate in hands-on installing and running of the experiments. We also attract many undergraduate students who spend summers at CERN and work with us at MIT. In the summer 2007 we had undergraduates (including Philip Ilten) working on lepton identification using “standard candles” in pp collisions and on using γ+jet heavy-ion events for the studies of jet quenching.

Philip Ilten at CERN with the Globe of Science and Innovation in the background.

My name is Philip Ilten. As an undergraduate student at MIT, I always realized that students had amazing research opportunities, but I never dreamed that I could work at CERN on CMS. I have now spent the past two summers here, and am entering my senior year at MIT. Last summer I worked on measuring the Z to mu mu cross-section from Monte Carlo, and this summer I have been working on optimizing the tau identification algorithm. I also was able to come last January and worked on developing a shift monitor for the HLT.

Being here has not only taught me physics, but given me the chance to meet students my age from all over the world, gain some new perspectives, and travel around Europe. I also brought my racing bike this summer so I have been biking all over France and Switzerland. A few weeks ago I biked around Lake Geneva, and when the Tour passed by Geneva I made sure to see it. The summer students here are quite active, and for the past few months we have been playing Ultimate Frisbee a few times every week; a great way to temporarily escape physics and end the day. The parties are also quite fun and culturally diverse.

While I have to go back to MIT at the end of the summer I hope to return soon to CERN as a graduate student.

Download a podcast with Philip
(~ 23 Mbyte mp4 file)

Forward pixel commissioning detector during insertion into the strip tracker.

The extreme complexity of the CMS experiment makes it difficult to foresee, with sufficient accuracy, all the tiny integration details of all the subsystems of which this experiment is made. It’s therefore necessary to test as much as possible on the surface before the final underground integration at P5 can occur. To further this objective, an integration test of the forward pixel and strip tracker was planned. Despite the inauspicious day, the forward pixel commissioning detector was successfully inserted into the strip tracker on Friday the 13th of July at the Tracker Integration Facility at the CERN Meyrin site. During the following two weeks many tests were performed to learn as much as possible about various aspects of the integration: mechanics, electronics, and software. The forward pixel commissioning detector consists of the same type of mechanical and electrical components as the production detector but constitutes only a fraction of it: mechanically it represents a quarter of the final detector and 4% of the 18 million channels.

As shown in the figures, the forward pixel disks and services are mounted inside a carbon fiber half-cylinder. We tested the insertion technique of the forward pixel detector into the strip tracker which is accomplished by sliding the cylinder on two feet into the carbon fiber rails mounted in the strip tracker. We also tested the synchronous push-pull mechanism, with which two forward pixel half-cylinders are simultaneously inserted and removed.

Forward pixel commissioning detector inserted into the strip tracker.

We wanted to verify that noise is not injected by the strips into the pixel system and vice versa while the front-end electronics and services are running. Tests were performed with the pixels grounded to the tracker as well as completely ungrounded. No evidence was found of performance degradation or interference between the pixels and strips while running with one-quarter of the innermost TIB− layer.

Each forward pixel half-cylinder is assembled and tested at Fermilab (CMS Times – 20/11/06) before being sent to CERN where it is commissioned (CMS Times – 22/1/07). The successful completion of this test was made possible by the presence at CERN of a significant part of the forward pixel group combined with a profitable and enthusiastic collaboration with a team of strip tracker experts.

Forward pixel commissioning detector being reassembled at CERN. From left to right: M. Dinardo (Colorado), S. Kwan (Fermilab), and P. D’Angelo (INFN-Milano).

Submitted by:

Mauro Emanuele Dinardo

Combined HE/EE/ES BT2007 completed data taking

On August 14 the Combined BT2007 of Endcap Calorimetry, initiated by RDMS CMS and supported by CMS management, and HCAL, and ECAL communities, successfully completed a long term of about 2 month data taking Run. This test continued the RDMS tradition of combined test of the CMS Endcap detector prototypes since 1995. In respect to the very first 1995 combined test, which was very important for optimisation and integration of each detector and full inner Endcap system, the main goal of 2007 beam test is calibration of the Endcap Calorimetry in configuration similar to the real CMS experiment.

Three detectors (ES, EE, HE) installed at the rotation table at the H2 beam line of the CERN SPS.

Combined set-up, includes three distinct detectors: Preshower (ES), endcap electromagnetic calorimeter (EE), and endcap hadron calorimeter (HE), installed at the rotation table at the H2 beam line of the CERN SPS.

The assembly of EE prototype supercrystals by RDMS team in the CMS Crystal Palace.

The EE prototype consists of four supercrystals with 100 lead tungstate crystals in total, equipped with the full chain of readout electronics. It is a real prototype of the EE with cooling system, laser monitoring, DCS control, moderator and a full implementation of the safety system.

The Preshower (ES) prototype comprised two planes of Si-strip detectors with the full chain of readout electronics, attached to two planes of lead (to generate showers from incoming electrons/photons) - the same as the final configuration in CMS. For the first time the Preshower off-detector readout electronics (known as ES-DCC) were used, together with the XDAQ control and data acquisition software, online data quality monitoring and a full implementation of the safety system.

The HE prototype represents 20 degree sector of hadron calorimeter equipped with the final on-detector and off-detector electronics.

Each of HE, EE, and ES endcap detectors were calibrated standalone, and first time tested in the combined configuration very closed to the real CMS installation with various Very Low Energy and High Energy beams from 2 GeV up to 300 GeV, with a good identification of muons, electrons, pions, kaons, and protons.

3 independent HCAL, ECAL and Preshower x-DAQs, combined CMS DAQ with CMS Run Control, as well as 3 sub-detectors Data Quality Monitoring, in line with Combined Express Analysis, were used for tests.

Plot showing the signal in the detectors due to incoming electron beam.

In line with participation of many hardware and software experts, combined test also attracted many young physicists and students due to a good training for future operation with the CMS detector.

Preliminary data analysis is going on with CMSSW at CERN and Fermilab, and will be continued also in Dubna and Protvino.

Data taking Run is not the end of story, but only the first step with following data analysis, validation test of the simulation, and finally with calibration of the CMS Endcap Calorimetry.

On behalf of the Run Coordination Team, we would like to thanks and congratulate all participants, experts, shifters and all people who supported us during last 4 month since very beginning of preparation and performing of the combined test.

Submitted by:

Anatoli Zarubin

Action continues at Point 5; the HF has been taken out from its garage position in the cavern, for tests using the newly constructed raiser platform.

HF taken out from its position using the newly constructed raiser platform.

Inside and on the vac tank work continues on inner detectors cable installation and validation. Enormous effort is being invested into looking into each detail.

Central optical fibres installation in progress.

Validation of the installation.

Work on the high voltage cables for the RPCs is in full swing, handling the thick cables is quite a difficult task.

Preparations are going on in full earnest for the imminent August Global Run.

Submitted by

Archana Sharma

Visit to CMS, 26 July 2007

On 26th July, some Members of Parliament of the United Kingdom visited the CMS experiment at Point 5. They were introducted to CMS by Prof. Jim Virdee (CMS) and Prof. Jonathan R. Ellis (CERN).

Some of the distinguished visitors during their visit to CMS.

You can find some more photos from the visit here: http://cdsweb.cern.ch/record/1049115

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