The CMS experiment (exploded view)
CMS is the detector of one of the 2 multi-purpose experiments out of the 4 experiments located at the LHC at CERN near Geneva. CMS is installed at point 5 in Cessy.
Main goals :
During the last decades, research in particle physics has made tremendous progress and succeeded in validating the theoretical framework called “Standard Model”. Nevertheless, lot of questions remain opened: Why matter is in excess in our universe while it was produced the same amount of matter and antimatter at the Big Bang ? How elementary particles acquire their mass? Would we have to modify our understanding of matter and energy if we observe new processes or new particles? In particular, the field associated to the “Higgs boson” could have generated the mass of all other particles. Other new particles are expected in the framework of Standard Model extensions such as a particle to explain the Dark Matter component of the universe as suggested by measurements from astrophysics and cosmology, or particles from supersymmetry, extra-dimensions or mini black holes ?
The past and present analysis activities of the CMS-Saclay group covers several domains with a predominance for the physics of the Higgs boson. Precision measurements in the context of the standard model and the search for new particles constitute the other components of the analysis activities of the CMS-Saclay group.
For the CMS detector, the Saclay group is responsible for the design, manufacture and commissioning of the calibration system, by laser light injection, of the electromagnetic calorimeter (ECAL) with lead tungstate crystals and its permanent online monitoring. The group is also responsible for the development, commissioning and maintenance of the off-detector electronic system called the Selective Read-out Processor (SRP). For each event accepted by the first level of the experiment triggering system, the SRP makes it possible to alleviate in real time the quantity of calorimeter raw data before being sent to the acquisition system.
Concerning the upgrades of the CMS detector for the high-luminosity phase of the LHC i.e. the phase 2 upgrades for HL-LHC, the CMS-Saclay group is involved in the design, development and manufacture of the front-end electronics of the barrel electromagnetic calorimeter. In addition, CMS endcap calorimeters will be replaced for this HL-LHC phase. In May 2015 CMS opted for a radiation hard high granularity and dense silicon / tungsten calorimeter called HGCAL. The CMS-Saclay group in Saclay is involved in this project by taking the responsibility for the design and development of the precise LHC clock distribution system, including the TDC part of the HGCAL front end electronics, in order to ensure the synchronization of the HGCAL electronic channels and the precise determination of particles time of the flight. The development of the clock distribution system may go beyond the HGCAL framework and become generalized to other CMS detectors. The CMS-Saclay group is also involved in the study of jets trigger primitives algorithms for HGCAL and their implementation in firmwares (FPGA).
Irfu Contributions:
Coil:
Study, production follow-up , installation and validation of the solenoid (see the solenoid page)
Optical fibres system developed to uniformly distribute laser light to crystals during the follow-up of the crystal transparency of CMS-ECAL.
Electromagnetic calorimeter:
* R&D on photo-detectors APD (Avalanche Photo-Diodes) (Sédi/SPP)
* R&D on crystals (Crystal-Clear collaboration)
* Study, development, installation, test and data analysis of the crystal transparency monitoring system (Sédi/SPP):
Even if crystals used in CMS-ECAL are radiation hard, they suffer for loss of light transmission under irradiation due to colour centres creation in the crystal structure.
We have developed a system to measure in real time the transparency of each crystal which subsequently, permit to correct the detector response and thus stabilize it at the level of few per mille in order to be able to perform a physics calibration during a period of about one month.
This measurement is done by injecting laser light in front of each crystal and by reading the associated photo detector response. The amount of laser light send to the crystal is measured with a reference PN diode.
In order to reach the desired performances, we have developed a light distribution system with optical fibres associated to multilevel randomisation splitters to avoid propagation of laser speckles.
A specific electronics has been developed to read the reference PN diodes: a low noise preamplifier in DMILL technology (FEM) and a digitisation module with an interface with the CMS DAQ (MEM).
The SRP consists of 12 6U-VME cards, grouped in triplets. Each triplet processes the data coming from one ECAL partition.
* Study, development, installation, test and data analysis of the Selective Readout Processor (Sédi/SPP):
In the CMS experiment, a complete readout of the electromagnetic calorimeter represents a data block of 1.5 MB, which is bigger than the allowed size for the full CMS event.
In order to decrease the ECAL size by a factor of about 20 without introducing biases in physics analysis, we have developed the Selective readout Processor (SPR), which allow to readout only the relevant regions for each event.
The SRP receives the information from the trigger system through “trigger primitives” and send back to the data concentrator the basic unit numbers which will be fully read out. On the other regions, we perform a zero suppression.
The main difficulties in such a system are located at the level of the communications with the other ECAL parts. A protocol based on very high speed serial transfers with optical fibres has been implemented in this project. This offered the opportunity for the SEDI to extend its know-how in this strategic domain. This communication architecture has been later reuse in CMS by the Global Trigger team to develop a new system.
* "Squirrel":
Study, construction and commissionning of the facility (dubbed "squirrel") to introduce and install the EM calorimeter supermodules inside the CMS Barrel.
Triplet of VME cards of the selective readout processor developed for the CMS ECAL acquisition system.
Means of investigation:
To study the limits of the Standard Model and to answer the great questions of modern physics (origin and hierarchy of the masses, dark matter and dark energy of the universe, matter-antimatter asymmetry, ...) the conditions that prevailed at the beginning of the universe, i.e. very high temperature conditions, have to be reproduced. For this, the LHC accelerates protons to energies never reached to date and makes them collide frontally in the heart of large detectors like CMS.
This detector detects the product of these collisions and, analyzing them, can identify each type of event. The statistical comparison of each of these categories of events with the theoretical predictions makes it possible to confirm or invalidate various models.
Technical description:
The LHC produces proton-proton interactions every 25 ns, with more than a dozen collisions per interaction. This produces tens of millions of events to process per second. Moreover, since the events searched for are very rare, it is necessary to eliminate in real time the interactions without physical interest. This is achieved by a high-performance online selection system. To analyze the products of proton-proton collisions, it is necessary to have a detector capable of recognizing each type of particle produced.
Operation:
In CMS, an intense solenoidal magnetic field, produced by a superconducting coil, deflects the charged particles. A silicon trajectometer placed at the center of the detector makes it possible to measure the curvature of these trajectories and thus to reconstruct the momentum of the particles. Around the trajectometer is installed an electromagnetic calorimeter consisting of nearly 80,000 crystals of lead tungstate. It can measure the energy of photons, electrons and positrons. A hadronic calorimeter, placed around the preceding one, makes it possible to measure the energy of hadrons (protons, pions, kaons, ...). Outside the coil, the magnetic yoke that channels the magnetic field return lines is instrumented to detect the muons. The on-line selection of events is carried out using information from the calorimetric systems and the muon detection system. This system reduces the number of interesting events to 100,000 per second. The trajectometer information is used in a later phase during the detailed reconstruction of the events which allows to keep only a few hundred interesting events per second which are analyzed in detail in all the laboratories of the collaboration.
Specificities:
The whole setup forms a detector of 15 meters in diameter and 21.5 meters long for a mass of 12500 T.
Diphoton mass spectrum weighted by the ratio S/(S+B), together with the background subtracted weighted mass spectrum.
Physics analysis activities
One of the main goal of the LHC is the study of the breaking mechanism of the electroweak symmetry. The search for the Higgs boson(s) has been a major objective of LHC experiments and since the discovery of a Higgs boson in 2012, precise measurement of its parameters (mass, couplings) and the search for possible additional Higgs bosons have become new objectives. The LHC is also focused towards the precise measurement of many observables of the standard model as well as the search for new particles within the framework of its possible extensions.
The past and present analysis activities of the CMS-Saclay group covers several domains with a predominance for the physics of the Higgs boson. Precision measurements in the context of the standard model and the search for new particles constitute the other componentsof the analysis activities of the CMS-Saclay group.
The central theme concerns the physics of the Higgs boson with the inclusive search of a light standard Higgs boson decaying into two photons. Despite a very small decay rate, this mode has proven to be particularly important for discovery thanks to the narrowness of the signal peak above the continuous distribution of irreducible background noise from the association of two real and isolated photons produced in QCD events.
The narrowness of this peak stems from the energy and position resolution of the detected photons as well as the knowledge of the position of the collision point. In this analysis activity, the CMS-Saclay group benefits from its expertise in the optimization of the performances of the electromagnetic calorimeter, as well as the procedures for calibration and on-line monitoring of the lead tungstate crystals transparency.
Since the discovery of a Higgs boson in 2012 to which the CMS-Saclay group strongly contributed, this activity has expanded towards the study of the Higgs boson coupling to the standard model vector bosons for different production modes, the search for the ttH production mode with a Higgs boson produced in association with a pair of top quark top in the channel where the Higgs boson decays into two photons and finally the search for Higgs boson pair production with a Higgs boson decaying into two b quarks and the other into two photons.
The CMS-Saclay group also contributed to the search for a Higgs boson in the two tau leptons decay channel with one of the tau leptons decaying leptonically and the other hadronically. This search was also used to explore the parameter space of supersymmetric extensions where the decay into tau lepton pairs is dominant.
Concerning the standard model physics the CMS-Saclay group CMS has contributed to the study of events containing several gauge bosons leading to final states with several isolated leptons. These studies performed in Saclay focused on events with a pair of Z0 bosons events with four electrons or two electrons and two muons in the final state. At higher luminosity, it will be possible to exploit these events to precisely study three gauge bosons couplings of the electroweak theory. The Saclay Group also contributes very strongly to the measurement of the W as well as Z0 production cross-sections in association with jets. Finally, the CMS-Saclay group is involved in measuring the mass of the W boson.
Finally, the CMS-Saclay group is involved in the search for new particles especially through three types of data analysis. First, the search for heavy neutrino in the context of the so-called nuMSM extension of the standard model. Second, the search for supersymmetric particles such as the supersymmetric partners of the top quark on the one hand and the charginos / neutralinos (electroweakinos) i.e. the supersymmetric partners of the photon, W boson, Z0 boson and Higgs bosons on the other hand, and all these in the decay channels leading to multileptonic final states. Third, the search for a scalar particle, resulting from the possible existence of extra-dimensions, in the mono-photon, mono-jet and mono-W/Z channels This scalar particle can also be a candidate for Dark matter.
Combined observed and predicted m?? distributions for the ??h, e?h, ?h?h, and e? channels. The inset shows the corresponding difference between the observed data and expected background distributions, together with the signal distribution for a SM Higgs boson at mH = 125 GeV.
Intellectual production
Publications:
http://cms-results.web.cern.ch/cms-results/public-results/publications/
Theses
- Higgs boson production in the diphoton decay channel with CMS at the LHC: first measurement of the inclusive cross section in 13 TeV pp collisions, and study of the Higgs coupling to electroweak vectors. Thesis defended on 26/09/2016 by Martina Machet.
- Experimental constraints on light scalar field models in cosmology and particle physics (SNLS and CMS experiments). Thesis defended on 07/07/2014 by Jérémy Neveu.
- Search for Neutral Higgs Bosons decaying to Tau Pairs at the CMS experiment. Thesis defended on 25/09/2012 by Somnath Choudhury.
- Measurement of the Inclusive Production Cross Section of Prompt Photon Pairs with the CMS Detector at the LHC. Thesis defended on 30/09/2011 by Laurent Millischer
- Study of ZZ diboson final states in the leptons-neutrinos decay channel with the CMS experiment at the LHC at CERN. Thesis defended on 27/09/2011 by Matthieu Marionneau.
- Study and optimization of the performance of the electromagnetic calorimeter of the CMS experiment for physics at the LHC. Thesis defended on 16/07/2007 by Julien Descamps.
- Participation to the study of the calibration of the electromagnetic calorimeter of the CMS experiment and study of avalanche photodiodes. Thesis defended on 13/12/1999 by Véronique Da Ponte Puill.
The HL-LHC
During its shutdown scheduled for 2023-2025 (LS3), the LHC will be upgraded so as to be able to operate in its so-called high luminosity phase (HL-LHC).The HL-LHC should therefore operate at an instantaneous luminosity of 5 10 ** 34 cm-2s-1 and be able to provide an integrated luminosity of the order of 250/fb per year during about a decade which means about3000/fb of integrated luminosity. In these conditions, the pile up (PU) should increase to an average of about 200 interactions per beam crossing and will thusrepresent a major challenge for CMS experiments. Similarly, the degradation of performance due to the integrated radiation dose (300 kGy of absorbed dose or 3 Gy / h) should be carefully evaluated.
To face these challenges the CMS experience will engage in a second upgrade phase (phase 2 upgrades). These upgrades will concern several major componentsof CMS in particular the trajectometer, calorimetry, the muon system and the triggering system so as to be able to cope with the PU without increasing the thresholds unreasonably from the point of view of physics and with the prospectof including the trajectometer already at the level 1 for the triggering system.
CMS calorimeters
Calorimetry is a critical element of CMS for physics at the HL-LHC. It allows to identify and reconstruct photons and of electrons as well as measure jets and missing transverse energy. Indeed the technique of particle flow (PF) makes it possible to measure jets and missing transverse energy by combining the information from the Trajectometer and calorimetry. Under high PU conditions the particle flow technique requires very good longitudinal and transverse segmentation to optimize the association of traces and energy deposits in calorimeters. A good reconstruction of these objects (photon, electron, jet and missing transverse energy) is paramount for the CMS experiment ability to continue the precise measurements of the Higgs boson properties and for the search for new phenomena beyond the Standard Model.
The electromagnetic calorimeter (ECAL) of CMS is a homogeneous calorimeterconsisting of 75848 scintillating crystals of lead tungstate located inside the CMS superconducting magnet. It is composed of a central part (barrel ECAL 60000 crystals) covering the region in pseudo-rapidity eta < 1.48and two endcaps (EndCap ECAL i.e. EC ECAL, 15000 crystals) which extends the coverage in pseudo-rapidity up to eta <3.
These calorimeters have been designed to allow for very good measurement and reconstruction of the aforementioned objects and carry out the physics program up to an integrated luminosity of the order of 300-500/fb over a decade until the LS3 stop. However, the conditions for operation of the HL-LHC i.e. of the order of 3000/fb of integrated luminosity, requires the capacity of the detectors active material and electronics to be re-examined to optimally maintain the reconstruction performance and fully carry out the physics program.
The impact due to irradiation in the barrel part of the ECAL after 3000/fb is of the order of the irradiation of the endcap parts after 30/fb. Irradiation should not therefore not be a problem for the crystals of the barrel ECAL and there is therefore no need to replace them. However, the barrel ECAL will be challenged by the level of PU , the increase of the noise of the photodetectors as well as by triggering efficiencies that will require upgrades of its electronics. It will be necessary to have a better granularity (single crystal) at the level 1 of the trigger system. The rates will also require to increase the bandwidth currently limited by the multiplexing of the information on the detector. It is also mandatory to be able to label the spikes so as not to saturate the level 1 trigger system.
The endcap part of the CMS calorimeter must be completely modified to withstand the large irradiation (300 kGy) and mitigate the effects of PU. In May 2015 CMS opted for a radiation hard high granularity (5D i.e. position,Energy time) and dense silicon/tungsten calorimeter called HGCAL. The HGCAL allows to exploit both the energy deposit topology measurements and the tracking capabilities for electromagnetic showers in a particle flow reconstruction for both the triggering system and the offline analysis.
CMS-Saclay group contributions to phase 2 upgrades
Concerning the upgrades of the CMS detector for the high-luminosity phase of the LHC i.e. the phase 2 upgrades for HL-LHC, the CMS-Saclay group is involved in the design, development and manufacture of the front-end electronics of the barrel electromagnetic calorimeter. In addition, the CMS-Saclay group in Saclay is involved in the HGCAL project by taking the responsibility for the design and development of the precise LHC clock distribution system, including the TDC part of the HGCAL front end electronics, in order to ensure the synchronization of the HGCAL electronic channels and the precise determination of particles time of the flight. The development of the clock distribution system may go beyond the HGCAL framework and become generalized to other CMS detectors. The CMS-Saclay group is also involved in the study of jets trigger primitives algorithms for HGCAL and their implementation in firmwares (FPGA).
The TDR for the calorimeters upgrades is currently being written in 2017 and submitted to the LHCC in 2017 for the barrel part and 2018 for the endcaps.
More than 2800 physicists and engineers from 200 institutes from 46 countries (January 2017)
Faces of CMS: Photomosaic (September 2013)
History and main milestones
- March 1992:
- Organization in Evian by EFCA of a meeting entitled "towards the experimental program of the LHC": 4 collaborations were put in competition. At that time CERN had only two large detectors at the LHC.
- Creation of the LHCC by CERN of a scientific committee for the LHC experiments.
- Merger of Ascot and Eagle into a single Atlas collaboration.
- October 1992: three letters of intent submitted to the LHCC
- June 1993, two experiments, CMS and Atlas, are homologated by the LHCC for a technical proposal
- 1994: beginning of international collaborations with the arrival of 270 American physicists in the CMS experiment and the accession of 1250 scientists, 132 institutions, 28 countries. The basics of the main project are laid down:
- Table of collaborations:
- Table of responsibility:
- Technical Table
- Financial Tables
- January 1996: The General Management of CERN approved the projects of CMS and Atlas with a budget limited to 475 MCHF (price of 1995). CMS approval and development of the MoU
TDR Chronology
- 1997: Magnet, calorimeter, muon spectrometer, electromagnetic calorimeter,
- 1998: The Tracker, 550 pages
- 2000: Trigger, Level 1, 600 pages
- 2000: Addendum to the Tracker
- 2002: Acquisition of data and 2nd level of trigger
- 2005: Computer Science
- 2006: Physics (volume 1), detector performance and software tools
- 2006: Physics (volume 2), physics performance
Chronology of the MoUs
- 1996 Interim
- 1998 Construction (distribution of responsibilities and organization)
- 2002 Maintenance and Operations
- 2005 addendum concerning computing
Highlights
- Highlight : The world's largest superconducting solenoid is in place (april 2005)
- Highlight : The world's largest superconducting solenoid is in place (december 2005)
- Highlight : The Crystal Baker (mai 2006)
- Highlight : World record for the superconducting solenoid of the CSM experiment (september 2006)
- Highlight : Cosmic success for CMS (december 2008)
- Highlight : Last results on the search for the Higgs boson (december 2011)
- Highlight : Higgs boson : 125 GeV otherwise none (april 2012)
- Highlight : Discovery of a new particle at the LHC ! (july 2012)
- Highlight : Union around the Higgs boson (march 2015)
- Highlight : Analyses of the LHC data continue at 8 TeV and just start at 13 TeV (august 2015)
- Highlight : The properties of the Higgs boson measured by the Atlas and CMS experiment combined for the first time (september 2015)
- Highlight : Atlas and CMS in search for new particles (june 2016)
Equipe de CMS à l'intérieur de la bobine
Main figures for CMS
Detector:
15 meters in diameter and 21.5 meters long for a mass of 12500 T.
Solenoid:
|
Magnetic field (T) |
4 |
|
Length (m) |
12.5 |
|
Cold Bore diameter (m) |
6 |
|
Total Ampere-turns (MAt) |
41.7 |
|
Stored energy (GJ) |
2.6 |
|
Axial force (MN) |
147 |
|
Maximal radial pressure (MPa) |
6.4 |
|
Nominal current (kA) |
19.14 |
|
Layers |
4 |
|
Conductor dimensions (mm2) |
64*22 |
|
Type of conductor |
reinforced NbTi |
Seen from far away, the entire magnet.
General view of the solenoid
CMS is one of the detectors of the 4 experiments (in addition to Alice, Atlas and LHCb) currently taking data at the LHC, the CERN protons collider near Geneva. CMS is located at point 5 of the LHC Collider.
To measure the energy of the particles one uses a magnetic field all the more powerful that the particles are energetic. The magnetic field of CMS is produced by an electromagnet which is in the form of a superconducting coil, 7 meters in diameter and 12 meters long, cooled at the temperature of liquid helium (-269 ° C). This coil is contained in a vacuum vessel intended to insulate it thermally. All this assembly is placed in the center of a steel structure of 12500 tons, for the flux return of the enormous magnetic field produced by this giant solenoid.
The Irfu, which is at the origin of the design of this superconducting solenoid, the biggest ever, was also in charge of the study and the responsibility of the follow-up of the processes of its assembly, going as far as creating dedicated tools for this purpose. The extremely complex assembly operations were carried out without major problems. This success also owes to the assembly teams at CERN and to the industrialists who provided various elements and who participated in their final assembly.
Collaborations:
Main participants in the solenoid:
Countries:
- Italy
- France
- Swiss
- United States
Laboratories:
- Cern: general coordination for CMS collaboration, external cryogenics, electrical power circuit, instrumentation.
- CEA-Irfu: General studies of cold mass, coordination of its assembly, detailed study of certain components and industrial monitoring of their realization, tests of critical components.
- ETH Zurich: drivers.
- INFN Genoa: winding.
- University of Wisconsin
French collaboration for the CMS Magnet:
- Air Liquide (refrigerator)
- Techmeta (driver reinforcement)
- SDMS (cryogenics)
- Lenoir-Elec (power contactors)
- Franc-Comptoise Industrie (assembly of the cylinder head at CERN)
- Velan (magnetic flap)
Assembly of the five coil modules in February 2005
Scientific Approach
Specificities
The largest superconducting solenoid ever built (6m internal diameter, 12.5 m long) and the most powerful (4 Teslas central field, stored energy of 2.7 GJ).
Contribution of Irfu
Scientific and technical responsibilities:
- General study of the cold mass
- Detailed study of certain components and industrial monitoring of their realization (suspension ties, thermal screens, proximity cryogenics, power supply)
- Testing of critical components (prototypes of electrical junctions, current leads, suspension ties, cryogenics)
- Coordination of the assembly of the cold mass
- Participation in tests in the surface hall
Progress and perspectives
Important dates:
- 1996 to 1997: General organization of the CMS collaboration (PDR and TDR)
- 05/1997: Technical Design Report
- 12/1998: Engineering Design Report of the coil
- Early 2000: construction of the first elements of the cold mass
- From May 2000: Arrival at CERN of the cylinder head (external armature). This marks the beginning of the assembly of the detector in the surface hall
- Early 2005: arrival of the 5th and last module at CERN
- Summer 2005: Introduction of the cold mass in the magnetic circuit
- February 2006: Magnet put in cold and brought to its nominal temperature
- Mid-July 2006: Start of electrical tests; First detections of cosmic rays
- End of August 2006: the solenoid reaches its nominal field of 4 Teslas
- End of October 2006: measurement of magnetic fields at different field levels
- November 2006: end of the surface tests. Beginning of descent of the elements of the magnet into a cave
Outlook:
- Current 2007: Descent and installation in cave of all the elements of the
cylinder head, as well as other elements of the detector
- End of 2007: cooling in the cave, low current tests
- 1st quarter 2008: rise to nominal field in the cave
Scientific and technical assessment
All the tasks performed by Irfu were carried out technically and in accordance with the general planning of the magnet.
Highlights
- Switching of the CMS vacuum vessel (July 2002)
- End 2005: insertion of the cold mass of CMS in the cylinder head
- End of August 2006: the nominal magnetic field of 4 Teslas is reached
The Saclay team before the start of the cooldown in February 2005
Artistic view of the solenoid
Contact
More information
The CMS experiment is installed at the LHC proton collider at Cern and has begun its data taking campaign in 2009.
The electromagnetic calorimeter was designed to initially allow for low luminosity discovery of the Higgs boson decaying into two photons. The CMS has a very compact electromagnetic calorimeter with a very good energy resolution
The contributions of Irfu
Scientific and technical responsibilities of Irfu
- Design, manufacture and commissioning of the calibration system, by laser light injection, of the electromagnetic calorimeter with lead tungstate crystals.
- R & D on APD photodetectors (avalanche photodiodes)
- R & D on crystals (Crystal-Clear collaboration)
- Study, development, installation, testing and exploitation of the crystal transparency monitoring system data.
- Study, development, installation, test and exploitation of selective read-out processor data
- Study, fabrication and implementation of the supermodule loading system of the electromagnetic calorimeter in the CMS experiment.
Experimental means
The electromagnetic calorimeter consists of more than 75,000 lead tungstate crystals. The central barrel consists of 18 supermodules arranged in phi in each half plane. Each supermodule contains 4 modules of 400 crystals each. The two endcaps contain 14648 crystals. Each crystal of the central barrel is read by 2 APDs (Avalanche Photo Diodes). Each crystal of the endcap is read by a VPT (Vacuum Photo Triodes).
Technical description
Laser light injection system to follow crystal transparency.
Optic fibers distribution system.
PN diodes calibrate the laser light received by group of 200 crystals.
Specificities
PN diodes must withstand radiation doses equivalent to 10 years ofLHC at high luminosity. At high luminosity, the crystal response is assumed to decrease by 3-5% in the first few hours and then saturate. In the absence of irradiation, the crystals recover. The loss of transparency is corrected in the short term (20 to 30 minutes) with an accuracy of 0.4%.
Collaborations
Collaboration CMS (Compact Muon Solenoid): more than 2800 physicists from 200 institutes from 46 countries.
The main laboratories that share the design and construction of the central barrel of the electromagnetic calorimeter are Caltech, Cern (Geneva), CEA/DRF/Irfu, INFN Milan, INFN Rome, IPNL Lyon, LLR Palaiseau, Zurich-ETH
Status and perspectives
Important Dates
- 1998: approval of the Technical Design Report of the electromagnetic calorimeter (Ecal) by the CERN LHCC.
- 1999: fabrication and characterization of pre-assembly elements of the calibration system of the electromagnetic crystal calorimeter.
- 1999 - 2002: manufacture and characterization of the standard elements of the calibration system.
- 2002 - 2005: preliminary calibration of the crystal calorimeter at Cern from baem tests.
- End 2003: The 25 micron technology was chosen by Ecal as the basis of the front-end electronics. 10 assembled supermodules.
- October 2004: Realization, calibration and tests of the supermodule 0
- Mi-septembre 2005: half of the barrels made
- December 2007: barrel in the cave
- June 2008: End of assembly of the endcaps
- 10 September 2008: Circulation of the first beam in the LHC
Scientific and technical assessment
Scientific evaluation: Scientific Council of the SPP on 24-26 / 09/2001, 28/04/2002, 03/07/2003, 04/11/2011, 13/11/2013, 30/11/2015.
Highlights
2002: Precalibration of a module of the calorimeter (400 crystals); Beam validation of the calorimeter monitoring system.
2003: start of assembly of the light distribution system on the series modules; Realization of a prototype of the calorimeter read-out system.
Contact
Mr. DEJARDIN
Goal
The main objective of the CMS Electronique project is the development of an electronic device called the selective read-out processor for the electromagnetic calorimeter (SRP for Selective Read-out Processor) of the CMS experiment. The SRP is part of the read-out electronics of the "Off-Detector" calorimeter due to its location in the underground service cavern outside the experimental cavern. For each event accepted by the first level of the trigger system of the experiment, the SRP must allow to decrease in real time the quantity of calorimeter raw data before being sent to the acquisition system. In spite of a considerable reduction factor (from 15 to 20) to be obtained, the physical performance of the calorimeter must not be compromised.
Themes and programs
Innovation for detection systems / Signal processing and real-time systems
Collaboration
The design and realization of the off-detector electronics are shared between the following laboratories:
- Cern: configuration boards for front-end electronics and clock distribution and various control signals;
- Irfu: Selective Read-out Processor boards SRP
- LLR Palaiseau: maps of trigger primitive generation
- LIP Lisbon: memory buffer boards
Means of investigation
- Study of parallel optical technologies and very high speed serial links of FPGA electronic components. These technologies are proposed for communication links of the SRP with other subsystems of the off-detector read-out electronics
- Study of the use of embedded processors in the new generation FPGAs
- Study of selective read-out algorithms and their performance
Tools
Industrial development kits and associated software for the parallel optical components and new generation FPGAs. Very high performance serial link analyzer.
Specificities
- great number of PRS input / output links - about 200;
- High bandwidth - 1.6 Gbit / s (see 2.5 Gbit / s) per link;
- Asynchronous operation at level 1 trigger frequency - up to 100 kHz;
- Limited time budget - 5 -Fìs;-A
- Flexibility in selecting selection algorithms using FPGA type programmable wired logic.
The SRP consists of 12 identical boards complying with the VME64x standard. Each board can be used for the barrel and endcap regions of the electromagnetic calorimeter. It can also serve as the test instrument for other SRP boards.
Contribution from Irfu
Scientific and technical responsibilities
-
Coordination of the collaboration "Off - Detector Electronic" at Cern;
-
Definition of selective read-out algorithms;
-
Definition of the global architecture of the selective read-out device;
-
Definition of the communication links of the SRP with other subsystem of the Off-detector read-out electronics;
-
Design and implementation of the SRP.
Study of selective read-out algorithms
Design and implementation of the selective read-out device
Status and perspectives
Important Dates
- April 2002: Association of Irfu (at the time DAPNIA) with the "Off-detector Electronics" collaboration
- June 2003: Launch of the CMS Electronics project at Irfu
- September 2003: Participation in the "Addendum to CMS ECAL Technical Design Report"
- December 2003: Validation of parallel optical technology for SRP communications links
- May 2004: Review by the CMS collaboration of Electronics System Review: approval of the architecture of the SRP
- June 2004: Demonstration of the operation of the SRP under the temporal constraint of 5-Fìs-A
- November 2006: "SRP Electronics system review" at CERN: demonstration to the evaluation committee of the operation of the SRP on two prototype boards; Agreement for mass production of final boards
- January 2007: Launch of series production
- March 2007: Tests at CERN in a subset of the non-detector electronics
- June 2007: End of production of SRP final boards
- August 2007: End of serial production of SRP boards
- September 2007: Installation of SRP "Barrel" boards at Cern
- February 2008: Installation of SRP "Endcap" boards at Cern
- June 2008: Integration of the "Barrel" SRP boards into the ECAL read-out system
Highlights
- June 2004: Validation of the parallel optical technology for the communication links of the SRP and validation of the operation of the SRP under the temporal constraint of 5-Fìs-A
- December 2006: End of the prototyping phase
- June 2007: End of production of SRP final boards
Contact
• The ultimate constituents of matter
• The Electronics, Detectors and Computing Division • The Particle Physics Division • The Systems Engineering Division
• CMS
