A warm and early October afternoon saw the beginning of the 2005 ATLAS overview week, which took place Rue de La Montagne Sainte-Geneviúve in the heart of the Quartier Latin in Paris. All visitors had been warned many times by the ATLAS management and the organisers that the premises would be the subject of strict security clearance because of the "plan Vigipirate", which remains at some level of alert in all public buildings across France. The public building in question is now part of the Ministúre de La Recherche, but used to host one of the so-called French "Grandes Ecoles", called l'Ecole Polytechnique (in France there is only one Ecole Polytechnique, whereas there are two in Switzerland) until the end of the seventies, a little while after it opened its doors also to women.
In fact, the setting chosen for this ATLAS overview week by our hosts from LPNHE Paris has turned out to be ideal and the security was never an ordeal. For those seeing Paris for the first time, there were many sightseeing possibilities within walking distance, as well as a variety of restaurants offering a wide choice of international food. For the social events, ATLAS participants were offered a visit of musÁe de Cluny and a meal in the Senate at Luxembourg, during which the too-slow or too-engaged in fascinating conversations probably did not get a chance to sample all the tidbits served at high speed by a host of professional waiters.
Sitting down in the main auditorium revived thirty-year old memories of days when, as students, we used to visit this particular auditorium exclusively at times when the military management of the school wished to impart its collective wisdom to us through seminars by four-star generals on the Red Peril (sic!) or to submit us to military aptitude tests (not considered by them to be an oxymoron). The more mundane scientific lectures, such as topology in mathematics by Schwarz or quantum mechanics by Gregory, were relegated to austere and less comfortable auditoriums. Jean Iliopoulos brought me back from my reminiscent mood with his very vivid flashback through the major historical landmarks in the progress of theoretical particle physics over the past century. His main focus was on the treatment of infinities and symmetries and his beautiful and inspiring talk led even him to be carried away somewhat and to answer the question: "What if nothing is found at the LHC?" with a "But this is impossible!" from the heart, followed by a more rational "I would be very surprised!"
The format of this overview week has departed already significantly from that of the past ones, when the main progress to report on dealt mostly with construction aspects of the various components of our huge and challenging detector. The focus is now gradually shifting towards that of a real experiment with its main challenges of integration, installation and commissioning in all areas from detector to trigger and data acquisition and to computing and physics analysis. The progress of the latter was described in several talks which reminded in particular the audience of 250 people or more that the Rome ATLAS Physics Workshop in June of this year saw a record attendance of 450, hinting at what is to come once real data will be available to the collaboration.
The data challenges and computing efforts which led to the Rome workshop have certainly demonstrated that an ever wider community is now becoming available to grapple with the rapidly developing tools for simulation, reconstruction and analysis. Many of the critical areas in our software lack the required effort to achieve the ambitious but mandatory milestones which must be met if our collaboration is to publish physics papers soon after the first data taking in 2007. Some of the issues which must be pursued with better organisation and more resources were glimpsed at when reading between the lines of the various reports from the Combined Test Beam: the precise calibration of our electromagnetic LAr calorimeter and the accurate alignment of our Inner Detector and Muon Spectrometer components will have to be done on a much larger scale and much faster than what has been achieved for the Combined Test Beam data. These data have certainly already provided multiple rewards to those who contributed to this huge effort in all areas: they have paved the way for developing the tools and procedures required for the reconstruction of real ATLAS experimental data in terms of the calibration and alignment issues never before addressed in any realistic way in our collaboration.
Closer to the detector itself, the trigger and data acquisition systems have also progressed considerably on all sides, from hardware specifications and procurement to software development over the past year:
the construction of the level-1 calorimeter and muon trigger systems is well advanced with a number of Local Trigger Processors and ROD Busy Modules available for delivery to the detectors and a very intense activity of installation of on-detector electronics for the barrel and end-cap muon systems,
most of the trigger software, from level-1 emulation to high-level trigger algorithms and steering infrastructure is now available in the offline releases for detailed validation and integration work. Large-scale tests in a realistic environment (700 nodes corresponding to 25% of the full ATLAS TDAQ system have by now validated the choice of Athena, the offline framework, for the actual operation of the level-2 and event-filter algorithms in ATLAS, but have also uncovered and solved some problems not seen earlier during similar medium-scale tests), and
activity at point 1 is ramping up considerably to install and commission a full pre-series system, corresponding to 10% of the final system.
On the detector side, tremendous progress was reported in multiple areas of integration:
in SR1 for the Inner Detector, where the four barrel SCT cylinders have been received after assembly in Oxford, tested and found to be fully functional at the level of 99.6% of all strips, and assembled together within their thermal enclosure. At the same time, the barrel TRT has recorded its first cosmics ray events after successful completion of the integration of all the front-end electronics boards (see corresponding articles in this issue of the ATLAS eNews). The only clouds on the horizon for the Inner Detector arise from the recent discovery of corrosion in the barrel pixel cooling tubes and from the very tight integration schedule for the second end-cap.
in building 180 for the LAr end-caps and end-cap toroids. One LAr end-cap has undergone successful cooling down, testing and has now been transported to point 1 in anticipation of its imminent descent into the pit. The second LAr end-cap is very near the end of its integration process and will join its twin soon if all goes well. The first half of the cold mass for end-cap toroid A has been assembled and most of the magnet team efforts are now focussed on timely delivery of both end-cap toroids to point 1 during 2006.
and in BB5 (resp. B180) for the barrel (resp.) end-cap muon chambers. Many barrel assemblies composed of RPCs and MDTs are now ready for installation in ATLAS. The first sectors of TGC and MDT chambers for the big end-cap wheels have been assembled and tested (see corresponding article in this issue of the eNews).
All these considerations are dwarfed on one side, amplified on the other by the huge progress reported on the installation and commissioning in the ATLAS pit:
dwarfed on one side, because the reports from Technical Coordination and the detector systems demonstrated dazzlingly the tremendous pace of work achieved the last year, as exemplified by the completion of the mechanical installation of the barrel toroid and the recent movement of the barrel calorimeter to its final position in the experiment. As perhaps the most striking achievement of this past year, despite the staggering complexity of the engineering endeavour, the release of the mechanical constraints on the barrel toroid has led to coil movements as predicted by calculations to better than 10 mm, a result confirmed by the interpretation of the detailed survey measurements and by the available active alignment sensor measurements recorded during the last phases of the barrel toroid installation.
amplified on the other side, because the excruciatingly detailed and painstaking work ongoing in the ATLAS pit in terms particularly of service installation, of positioning strategy and survey of the various elements, reminds the software experts and the physics community at large of the huge amount of additional work to be done over the coming year to simulate a realistic ATLAS detector as installed and to reconstruct the simulated data using validated and optimised calibration and alignment procedures. Only then will the collaboration be in a position to demonstrate convincingly to all its eager participants that it can analyse data resembling those which hopefully will find their way from the detector to permanent disk storage during 2007.
Many of us have by now used the outreach tools under development in ATLAS for visits at point 1 and during the CERN Open Day in 2005 or at our home institutes and they have been hugely appreciated by all audiences, from the public at large to the connoisseurs. In particular, the DVD being developed to show in parallel the installation of ATLAS in virtual reality and accelerated Webcam sequences of what actually happened is a wonderful tool to explain our endeavour and transmit some of our enthusiasm for our science. Even more ambitious outreach tools are now under active development to guide the spectator through the components of the ATLAS detector, almost as if he or she were a particle emerging from the interaction point. The actors in this effort deserve all our support and feedback as well as our congratulations for the work achieved so far.
After more than 15 years of preparation, we are all becoming more and more excited at the imminence of first serious data recorded with major parts of the ATLAS detector, as highlighted in several of the presentations towards the end of the week. At this moment in time, it is almost as enthralling to observe first physics signals from cosmic rays in the Tile calorimeter, in a sector of the muon chambers or in the TRT, as it is to wonder how many reconstructed top events will be observed above the background (even without b-tagging!) towards the end of 2007.
Computing Coordination - Report on Tier-0 Scaling Tests
To get prepared for handling the enormous data rates and volumes during LHC operation, ATLAS is currently running so-called Tier-0 Scaling Tests, which were started beginning of November and will last until Christmas. These tests are carried out in the context of LCG (LHC Computing Grid) Service Challenge 3 (SC3), a joint exercise of CERN IT and the LHC experiments to test the infrastructure of computing, network, and data management, in particular for its architecture, scalabilty and readiness for LHC data taking.
ATLAS has adopted a multi-Tier hierarchical model to organise the workflow, with dedicated tasks to be performed at the individual levels in the Tier hierarchy. The Tier-0 centre located at CERN will be responsible for performing a first-pass reconstruction of the data arriving from the Event Filter farm, thus producing Event Summary Data (ESDs), Analysis Object Data (AODs) and event Tags, for processing calibration and alignment information, for archiving both raw and reconstructed data, and for shipping these data to ten Tier-1 centres around the world. More information about the Tier model can be found in the ATLAS Computing Model, described in the ATLAS Computing TDR.
To get an idea of the data rates and volumes the Tier-0 centre has to cope with during full LHC operation, have a look at the following table, which summarises typical operation figures.
Data Transfer Process
Transferred Files
Data Transfer Rate
Total Data Volume
Event Filter Farm to Castor (Disk)
17,000/day
320 MB/s
27 TB/day
Castor (Disk) to Castor (Tape)
37,000/day
440 MB/s
38 TB/day
Castor (Disk) to Reconstruction Farm
190,000/day
340 MB/s
Reconstruction Farm to Castor (Disk)
190,000/day
140 MB/s
Castor (Disk) to Tier-1 Centres
85,000/day
720 MB/s
62 TB/day
Nominal data transfer rates during full Tier-0 operation
Our focus in the current Tier-0 scaling tests is mainly on achieving as high a data throughput as possible. For this purpose we have set up a system which is able to perform all basic Tier-0 operations concerning data management (registration, archival, transfer), which provides data-driven automatic job definitions, involves realistic file sizes, etc. For the time being, we have to simulate the dataflow from the Event Filter, though; this part will be exercised in later Tier-0 tests to come. We have two versions of software to run: first, a model that produces random data on-the-fly, which does not require much CPU time, but allows us to maximise the data throughput; and second, a trimmed version of real ATLAS-Athena reconstruction software, which meets the nominal performance requirements (e.g., on CPU time per event and output event sizes) foreseen in the ATLAS Computing Model, and which will also allow us to additionally test features like database access loads, writing event Tags, uploading Tags to a Tag database, etc.
Already in the first week of our Tier-0 scaling tests, we reached almost 10% of the required nominal transfer rates. We could increase performance to almost 20% (for transfer from Tier-0 to Tier-1 centres) and 30% (for Tier-0 internal data transfers), respectively, in the second and third weeks, and were able to sustain those rates for many hours. The figures below show monitoring snapshots taken during one of those successful runs.
Monitoring snapshots from Tier-0 data transfer exercise, taken on November 18, 2005. The first plot shows the transfer from the Tier-0 at CERN to up to five different Tier-1 centres. The second plot displays the data transfer within the Tier-0 centre (Event Filter into Castor; Castor to reconstruction farm; reconstruction farm into Castor).
Not all of the ten Tier-0 centres were included from the beginning in our tests. Nevertheless, what we consider particularly encouraging, to some of them we could reach transfer rates already close to the final commitments they have made in the Computing Memorandum of Understanding (MoU).
But we aim at even more, and there is still a long way in front of us... During the remaining weeks in December, we will try to push the system to its limits, to as high a data throughput as possible, involving all ten Tier-1 centres. This will then also help us in understanding the limitations of the current system and infrastructure, and in improving it (or providing feedback to IT and the Tier-1 centres to have it improved), where necessary. The future Tier-0 tests, which are planned for next year, will profit from this experience.
M. Branco - CERN
D. Cameron -
CERN
L. Goossens -
CERN
A. Nairz -
CERN
Pit Area - Last Few Metres for the Barrel Calorimeter
On Friday 4th November, the ATLAS Barrel Calorimeter was moved from its assembly point at the side of the ATLAS cavern to the centre of the toroidal magnet system. The detector was finally aligned, to the precision of within a millimetre, on Wednesday 9th November.
The ATLAS installation team, led by Tommi Nyman, after having positioned the Barrel Calorimeter in its final location in the ATLAS experimental cavern UX15.
The Barrel Calorimeter which will absorb and measure the energy of photons, electrons and hadrons at the core of the ATLAS detector is 8.6 meters in diameter, 6.8 meters long, and weighs over 1600 Tonnes. It consists of two concentric cylindrical detector elements. The innermost comprises aluminium pressure vessels containing the liquid argon electromagnetic calorimeter and the solenoid magnet. The outermost is an assembly of 64 hadron tile calorimeter sectors.
Assembled 18 meters away from its final position, the Barrel Calorimeter was relocated with the help of a railway, which allows the movement of these heavy detector elements at the centre of the ATLAS toroidal magnet. The movement gear consists of a hydraulic power pack, valve table and associated pipe-work, pressure and displacement sensors, and a computer control system. During movements, the detectors are supported vertically by air-pads. Effectively on air, the friction is decreased so the detector slides on the railway with minimal force. Traction cylinders enable the movement of the detector horizontally along the rail. Blocking jacks are used for the final support and adjustments in the vertical direction.
In fact, the movement was performed downhill, since the LHC plane is not horizontal, such that there is a difference of 40 cm in height from one side of ATLAS to another. As a result, the traction cylinders actually worked as brakes, so that the Barrel Calorimeter, once set in motion, was sliding by itself thanks to gravity.
The operation was computer-controlled by a PLC (Programmable Logic Controller) system, which reads in sensor data and displays this information for the operator, who can then steer the movement of the detector. The PLC also monitors the safety systems and has a self-levelling feature to maintain constant height during the movements.
The entire procedure of sliding the Barrel Calorimeter along the 18 meters of railway was performed over 12 hours at a constant speed of 4 mm/s. The most time-consuming operation was the recurrent procedure of reconnecting the traction cylinders to new railway anchoring positions. Accelerometers were installed to register all possible shocks above 0.02g, and to monitor that no such events occurred.
Aligning the Barrel Calorimeter into its final position is a major milestone for ATLAS, as this is the first set of detector elements to be placed in their final running position. The Barrel Calorimeter will support the Inner Detector, underlining the importance of high precision in its positioning. A large effort by the CERN survey team in an iterative alignment process made it possible to confirm the final position on 8 targets to a precision below 1mm. However, it is already known from measurements that the ground of the ATLAS cavern is rising. Re-adjustments are already foreseen, in case the natural forces push the Barrel Calorimeter away from the interaction point.
With this final act, the Barrel Calorimeter has landed in its final position, after years of construction at various home institutes, long journeys, as far as from Japan, assembly work at CERN and many laboratory and beam tests.
This article first appeared in the CERN Bulletin, Issue No.48-49 (28 November 2005).
T. Nyman -
CERN
J. Grudzinski - Argonne National Laboratory
As reported in the April 2005 issue of the ATLAS eNews, the first of the four Semiconductor Tracker (SCT) barrels, complete with modules and services, arrived safely at CERN in January of 2005. In the months since January, the other three completed barrels arrived as well, and integration of the four barrels into the entire barrel assembly commenced at CERN, in the SR1 building on the ATLAS experimental site, in July. Assembly was completed on schedule in September, with the addition of the innermost layer to the 4-barrel assembly.
Work is now underway to seal the barrel thermal enclosure. This is necessary in order to enclose the silicon tracker in a nitrogen atmosphere and provide it with faraday-cage protection, and is a delicate and complicated task: 352 silicon module powertapes, 352 readout-fibre bundles, and over 400 Detector Control System sensors must be carefully sealed into the thermal enclosure bulkhead.
The team is currently verifying the integrity of the low mass cooling system, which must be done before the enclosure cover panels can be fitted and leak tested.
Once this work is completed, the SCT barrel will be ready for insertion into the TRT barrel, which is expected to happen early next year. Then the combined system will be ready for testing in SR1 before being lowered into the ATLAS cavern in mid-2006.
The second-smallest barrel being inserted into the SCT 4-barrel assembly.
The completed assembly.
L. Batchelor - Rutherford Appleton Laboratory
J. Pater - The University of Manchester
"I had a great day in August when I went into SR1," said Daniel Froidevaux, former project leader of the ATLAS Transition Radiation Tracker, "not only had all SCT barrels arrived at CERN, but there were cosmic ray tracks seen in the TRT!"
Daniel's excitement was mirrored by the rest of the TRT collaboration when, on July 29, the first cosmic ray tracks were seen in the barrel. Along with many others in the community, Daniel was quick to point out that this is the cumulative result of years of R&D, test beam work, and an intense installation and integration schedule. Indeed, the cosmic ray readout is only possible through the coordination of many efforts, from detector mechanics to module assembly, power and high voltage control, cooling, gas systems, electronics and cabling, data acquisition, and monitoring.
"Many people have worked very hard on the the TRT, some of them for more than 10 years," said Brig Williams, the leader of the UPenn group responsible for much of the TRT front end electronics. He made sure to mention, though, that it required the help of quite a few "younger scientists, who have worked tirelessly to make it a reality."
Just as the final electronics were installed on the barrel of the TRT, which has over 50,000 straw tubes and 100,000 electronics channels, "system testing" began in July with cosmic ray tracking. The cosmic ray readout was then joined by an extensive program of threshold scanning, detailed timing tests, power distribution checks and more, all performed on 3 of the 32 stacks of barrel modules.
A powerful online monitoring tool currently allows for fast debugging of many problems related to noise performance, timing, and channel mapping, while offline tools are being developed in preparation for further cosmics running. Both methods will be crucial for evaluating detector performance, both above ground and after the detector is lowered into the pit in May of 2006.
Cosmics testing will take on even greater importance soon, as the SCT barrel is inserted into the TRT barrel. In late January, once the insertion is complete, combined testing will begin. This will be an important step for the Inner Detector community, as the different groups for services, detector controls, data acquisition, and monitoring all learn to work with each other. There is one thing that is certain: the months leading up to the installation in the cavern will be an exciting time.
Left: a cosmic ray track in the TRT barrel. Right: 2 cosmic rays in the upper half of the TRT.
During the summer of 2005 the last coils of the Barrel Toroid were installed in the cavern and the warm structure was completed. In October the top supports, which were used to hold up the coils in position during toroid assembly were removed. The top of the Barrel Toroid came down by about 18 mm under its own weight. With the installation of muon chambers and detector services, the top of the Toroid will go down by another 7 millimetres or so. The toroid then changed from the "egg" shape during installation to an (almost) circular shape. Remarkably the deflection observed is within the mm as predicted by calculation.
The installation and connection of the cryoring is making good progress at the moment. The cryoring, containing the superconducting bus lines between the coils and the cryogenic supply lines, inter-connects the vacuum vessels of the eight coils. On top of the Barrel Toroid the cryoring is connected to the current lead cryostat where the connections with the cryogenic system and the power supply are made. All tooling and platforms (the green and grey structures in the cavern) which were used during the assembly are almost removed.
Meanwhile the installation and commissioning of the magnet services (cryogenics, vacuum and electrical systems as well as controls) is going on as well. The 20.5 kA power supply and part of the bus bar system have been tested up to nominal current. The cryogenic system is also running and the storage dewar has been filled with liquid helium. The pumps which enforce circulation of liquid helium through the cooling tubes on the magnets operated already at their nominal flow. Installation and test of the vacuum system, control and safety systems are on schedule to be ready when the toroid will be closed by the end of next January. After a month of pumping and a month of cooling down the power test of the Barrel Toroid will commence in April 2006.
The last coil of the Barrel Toroid is put into position.
Looking through the Barrel Toroid, just before the barrel calorimeter is moved in.
The current lead cryostat is put into position, also visible is the chimney that connects the central solenoid (inside the liquid argon calorimeter) with the services (cryogenics, power).
Central Solenoid being connected
After completion of the Barrel Toroid assembly, the Central Solenoid was moved to its final position as part of the barrel calorimeter. It is now being connected to the chimney, the cryogenic and superconducting transferline leading to the exterior of the detector. In the last days of December the control dewar, a combination of cryogenic valve box and liquid helium reservoir, will be installed on top of the chimney to connect all external services. With this, the highest point of the ATLAS detector setup will be reached.
Connection of the solenoid to the chimney.
Integration of the End Cap Toroids made a big step forward
After a long time of fitting and measuring, the assembly of the first End-Cap cold mass made a big step forward. In hall 191 the eight coil modules and eight keystone box supports are put together.The bore tube is mounted in the middle and the whole assembly is now on the cantilever, which is used to support the cold mass when it is integrated with the vacuum vessel. Next the cryogenic and electrical connections between the coil modules have to be completed and instrumentation and thermal shielding have to be mounted. After a test in the spring of 2006, the first end cap will be transported to the cavern. After the installation underground a full power test is foreseen by the end of next summer.
Assembly of a sub module of one coil and two keystone boxes.
Muon Spectrometer - Surface Assembly of the End Cap Muon Spectrometer
Before the final installation in the ATLAS detector, the chambers of the inner and middle forward stations of the Muon spectrometer are integrated and assembled on large support structures. Work on the sectors of the Thin Gap Chamber (TGC) Big Wheels (trigger chambers) and of the Muon Drift Tube (MDT) Big Wheels (precision tracking chambers) started early this year, and has recently expanded to all the foreseen working areas, covering most the surface of building 180.
Several operations are performed, often in parallel, by different teams: final integration of the detectors, assembly of the support structures, installation and test of services, installation of chambers, and final tests. Control of the geometry is performed frequently both on assembly tooling and on complete sectors. The final tests verify the response of the detectors and of the electronics, including read-out and trigger electronics, the alignment system, and the detector control. The sectors are designed as a unit that can be fully commissioned, with a limited number of connections that are used now for the final tests, and will link it to the rest of ATLAS after the assembly of the Wheels.
The size of the sectors (10 m long and up to 8 m wide) requires the use of large mechanical tooling, which is also used during transport and assembly of the Wheels in the ATLAS UX1 cavern.
After the assembly is complete, each unit is kept vertical and stored in the same building. The assembly of the sectors forming the six TGC Big Wheels and the two MDT Big Wheels will continue during installation in the ATLAS hall, planned to start in spring 2006.
Top left: a TGC sector in storage. Top right: TGC working areas. Bottom: MDT sectors.
Miscellaneous - The ATLAS Education and Outreach Group
With the unprecedented scale and duration of ATLAS and the unique possibilities to make groundbreaking discoveries in physics, ATLAS has special opportunities to communicate the importance and role of our accomplishments. We want to participate in educating the next generation of scientific and other leaders in our society by involving students of many levels in our research. The Education and Outreach Group has focused on producing informational material of various sorts - like brochures, posters, a film, animations and a public website - to assist the members of the collaboration in their contacts with students, teachers and the general public. Another aim is to facilitate the teaching of particle physics and particularly the role of the ATLAS Experiment by providing ideas and educational material.
The Education and Outreach Group meets every ATLAS week, with an attendance of between 25 and 40 people. The meetings have become an interesting forum for education and outreach projects and new ideas.
The coming years: First Collisions in ATLAS
During the coming years the E&O work will primarily address the start up of the LHC and the ATLAS Experiment. The first collisions in ATLAS will become the major theme as we create activities and projects to focus attention on the expected physics to come from ATLAS. Preparations are underway to design these projects including a major educational project for students using ATLAS data. See coming issues of the ATLAS enews.
Status of informational materials
The Animation with three episodes
Episode 1: Shows the construction of ATLAS. It is practically finished.
Episode 2: Detecting particles in ATLAS. It shows how particles are detected in the inner detector, calorimeters, and muon system. Sound effects and narration are the major remaining work, but some animation is incomplete. Episode 3: The physics of ATLAS. The animation work has not yet started.
New DVD
The new DVD contains the film in English in high resolution, a preliminary version of Episode 1 with sound effects and narration, the web camera film, including the full toroid installation and high resolution photographs. The new DVD is for sale at the ATLAS secretariat for 5 CHF. Further DVDs will be available in the near future.
The Spin-off brochure
The spin-off brochure will feature applications of work by ATLAS physicists and will describe how ATLAS work has impacts beyond ATLAS on technology, computing, medicine, culture, and education. The brochure is aimed at the public and other interested people. The brochure will be finalised during spring 2006, but there will be a website with additional information.
The ATLAS exhibition in SX1
There is now an ATLAS exhibition in the building SX1, which is the starting point for tours of the ATLAS experimental area. The exhibition provides an introduction before entering the ATLAS cavern and gives an overview of LHC and ATLAS. It provides some details about ATLAS subdetectors from basic principles to more technical details.
New ATLAS film
The planned 2-3 year filming of ATLAS by former BBC producer Andrew Millington was presented by him at the Paris overview week. The film will focus on the sociology of ATLAS while following the construction completion, starting operation and the daily work of people. It will convey excitement and dedication, emphasising the human aspect. It will also follow aspects related to other sciences, industry, technology, as well asthe role of women. Full funding of the project is still pending.
Detector Images and ATLAS Logos
Images of the ATLAS Detector can be found here, and ATLAS Collaboration Logos can be found here.
M. Barnett - Lawrence Berkely National Laboratory
E. Johansson - Stockholm University
It is with great sorrow that we report that ATLAS Physicist Alexandru (Alex) A. Marin passed away November 14, 2005 in Geneva. He died after a courageous two-week struggle against necrotizing fasciitis, a very rare and rapidly progressing destructive infection. Employed by Boston University and working at Harvard University, Alex was a productive and popular member of the ATLAS muon detector group. He had been playing a leading role in the installation of end-cap muon chambers in Building 180 at CERN and was a long-term member of the ATLAS Muon Collaboration.
After the Boston Muon Consortium (BMC) MDT chambers were constructed and commissioned, Marin relocated to CERN in May 2005 to take on installation and commissioning responsibilities of the US MDT endcap chambers. He had spent the previous seven years employed by Boston University as a physicist with the BMC, and had worked with Steve Ahlen, Peter Hurst, Rick Haggerty and many others to assemble and integrate end-cap muon chambers. His work was of the highest quality, and he distinguished himself repeatedly with creative ideas for the chambers that will help them work well for many years at the LHC.
Alex spent his early career working on high energy physics and astrophysics experiments in his native Romania, the Soviet Union and CERN. He received his Ph.D. in Physics at the Central Institute for Physics in Bucharest in 1977. He was Principal Investigator for experiments carried out at CERN and at Dubna from 1974 - 1979, and from 1974 - 1983 was Principal Investigator for the Transition Radiation Experiment on the INTERCOSMOS 17 satellite, and for the ASTRO1 and ASTRO2 experiments on the Romanian Astronaut flight.
Alex moved to the United States in 1983 where he played leading roles in some of the more important large international experiments over the next 22 years. Altogether, Alex was co-author on 266 publications during a remarkably productive career that was carried out all over the world.
For MACRO he designed and built the laser calibration system for the very large array of liquid scintillators. MACRO did the most sensitive searches for magnetic monopoles and other exotic hypothetical particles, and was the first experiment to confirm the discovery of neutrino oscillations by the Super-K detector.
He worked on the PBAR and EXAM anti-matter balloon experiments, which contributed to the design of the AMS magnetic spectrometer that was later flown on the Space Shuttle.
For L3 at LEP he designed and built the radiation monitor for the silicon tracker and built a beam dump trigger for LEP. These devices kept the silicon tracker working safely for many years. L3 confirmed many results of the Standard Model of particle physics, and showed there are only three types of neutrinos in nature.
For LIGO, the sensitive gravity wave experiment, Alex designed and built environmental monitoring systems. LIGO is the first large scale interferometric detector to be built, and it will become increasingly sensitive over the coming decade as it searches for gravitational waves, predicted by Einstein's theory of general relativity.
In 1991, Alex, with Steve Ahlen and Bing Zhou, proposed and developed a muon system concept for the Superconducting Super Collider that was virtually identical to the one later chosen for ATLAS. For ATLAS he built 81 muon chambers and coordinated the construction of all these chambers. Alex developed many of the practical techniques needed to mass-produce these chambers with their highly demanding precision criteria. We expect that Alex's work on ATLAS will be his most enduring legacy.
Alex impressed all who knew and worked with him with his humor, grit, dedication, and courage. Some of his technical solutions were extremely simple but brilliantly effective. He was always willing to fight for what he thought was right, even when others would have compromised. He fought long and hard with considerable personal sacrifice to bring his wife and daughter to a new country for a better life.
On the very day when he became ill, he had gone to work despite feeling bad with a severe pain in his leg. Later that day he had to be carried by helicopter to the Geneva hospital where he lapsed into a coma a few hours later. This was characteristic of Alex - he had a nonchalance regarding his personal well-being, and his personal courage was demonstrated repeatedly through his career.
All of us had our favorite "Alex-Romanian" jokes and our favorite anecdotes about Alex (most of which involved his beloved dachshund Rexy, or his extraordinary talents as a driver of fast cars on narrow roads in Italy). He was a true hero of physics, and he will be missed very much by his colleagues and friends, who number in the hundreds, if not thousands. Alex is survived by members of his remarkable family, his father, two sisters, wife, daughter and grand daughter. He has been immortalized with the attachment of a plaque dedicating his contributions to sector C09 of the Big Wheel of the muon system.
Submitted on behalf of the friends and colleagues of Alexandru (Alex) Marin, by:
S. Ahlen -
Boston University
D. Levin -
University of Michigan
G. Mikenberg -
Weizmann Institute of Science
F. Taylor -
Massachusetts Institute of Technology
B. Zhou -
University of Michigan
