Просмотр кода страницы Компактный мюонный соленоид

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[[Файл:CMS Under Construction Apr 05.jpg|thumb|right|300px|Вид торца CMS через секции барреля. Лестница справа внизу даёт представление о масштабе.
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'''Компактный мюонный соленоид''' ('''CMS''' от {{lang-en|Compact Muon Solenoid}}) — один из двух больших универсальных [[Детекторы элементарных частиц|детекторов элементарных частиц]] на [[Большой адронный коллайдер|Большом адронном коллайдере]] (БАК) в [[ЦЕРН|Европейской организации ядерных исследований]] (ЦЕРН) в городе [[Женева]] ([[Швейцария]]).
Он расположен в подземном экспериментальном зале рядом с деревней [[Цесси]] на территории [[Франция|Франции]] недалеко от границы с Швейцарией.

Около 3600 человек из 183 лабораторий и университетов из 38 стран, включая Россию, составляют ''[[коллаборация|коллаборацию]] CMS'', которая построила детектор и в настоящее время работает с ним.<ref>[http://cms.web.cern.ch/cms/index.html Welcome to CMS] {{webarchive|url=https://web.archive.org/web/20090414011224/http://cms.web.cern.ch/cms/index.html |date=2009-04-14 }}</ref>

Детектор общего назначения, предназначенный для поиска [[Бозон Хиггса|бозона Хиггса]] и «[[Физика за пределами Стандартной модели|нестандартной физики]]», в частности [[тёмная материя|тёмной материи]]{{Переход|#Физическая программа эксперимента}}.

== История ==
<!-- Надо перевести далее например из английской статьи -->
В 2017 году коллаборация CMS отмечает своё двадцатипятилетие, в июне провела праздничное мероприятие<ref>{{Cite web |url=http://old.elementy.ru/LHC/novosti_BAK/433090/Kollaboratsiyam_ATLAS_i_CMS_ispolnyaetsya_25_let |title=Коллаборациям ATLAS и CMS исполняется 25 лет |access-date=2017-08-18 |archive-date=2019-02-02 |archive-url=https://web.archive.org/web/20190202152358/http://old.elementy.ru/LHC/novosti_BAK/433090/Kollaboratsiyam_ATLAS_i_CMS_ispolnyaetsya_25_let |deadlink=no }}</ref>.

== Физическая программа эксперимента ==
CMS предназначен для исследования различных типов физики, которые могли бы быть обнаружены в энергичных столкновениях на БАК. Некоторые из этих исследований заключаются в подтверждении или улучшенных измерениях параметров [[Стандартная Модель|Стандартной Модели]], в то время как многие другие — в поисках новой физики.<ref name="PhysicsatLHC">{{статья |заглавие=Поиск новой физики на большом адронном коллайдере |издание=[[Успехи физических наук]] |том=174 |номер=7 |страницы=697—725 |ссылка=http://ufn.ru/ru/articles/2004/7/a/ |язык=en |автор=Н. В. Красников, В. А. Матвеев |месяц=7 |год=2004 |тип=journal |издательство=[[Физический институт имени П. Н. Лебедева РАН|Российская академия наук]] |archivedate=2008-05-01 |archiveurl=https://web.archive.org/web/20080501142234/http://ufn.ru/ru/articles/2004/7/a/ }}</ref>

В апреле 2014 года коллаборация CMS сообщила, что [[ширина распада]] [[Бозон Хиггса|бозона Хиггса]] меньше 22 [[МэВ]]<ref name="el march 2015">{{Cite web |url=http://elementy.ru/LHC/LHC_results/higgs_study |title=Изучение бозона Хиггса |access-date=2015-12-16 |archive-date=2014-11-03 |archive-url=https://web.archive.org/web/20141103194941/http://elementy.ru/LHC/LHC_results/higgs_study |deadlink=no }}</ref>.

== Общее строение детектора ==

<!-- CMS is designed as a general-purpose detector, capable of studying many aspects of [[proton]] collisions at 14 [[TeV]], the [[Special relativity|center-of-mass]] energy of the [[Large Hadron Collider|LHC]] particle accelerator. It contains subsystems which are designed to measure the [[energy]] and [[momentum]] of [[photons]], [[electrons]], [[muons]], and other products of the collisions. The innermost layer is a silicon-based tracker. Surrounding it is a [[Scintillation (physics)|scintillating]] [[stolzite|crystal]] electromagnetic [[calorimeter (particle physics)|calorimeter]], which is itself surrounded with a sampling calorimeter for hadrons. The tracker and the calorimetry are compact enough to fit inside the CMS [[solenoid]] which generates a powerful magnetic field of 4 [[tesla (unit)|T]]. Outside the magnet are the large muon detectors, which are inside the return yoke of the magnet.-->

Строение CMS. В центре, в так называемом барреле, показан человек для масштаба. (HCAL — адронный калориметр, ECAL — электромагнитный калориметр)]]

== Строение CMS по слоям ==

Более полное техническое описание см. в [http://cdsweb.cern.ch/record/922757/files/lhcc-2006-001.pdf Technical Design Report].

=== Точка взаимодействия ===
<!-- This is the point in the centre of the detector at which [[proton]]-proton collisions occur between the two counter-rotating beams of the [[Large Hadron Collider|LHC]]. At each end of the detector magnets focus the beams into the interaction point. At collision each beam has a radius of 17 μm and the crossing angle between the beams is 285 μrad.

At full design [[luminosity]] each of the two LHC beams will contain 2,808 bunches of {{val|1.15|e=11}} protons. The interval between crossings is 25 ns, although the number of collisions per second is only 31.6 million due to gaps in the beam as injector magnets are activated and deactivated.

At full luminosity each collision will produce an average of 20 proton-proton interactions. The collisions occur at a centre of mass energy of 14 TeV. It is worth noting that the actual interactions occur between quarks rather than protons, and so the actual energy involved in each collision will be lower, as determined by the [[parton distribution functions]].

The first which ran in September 2008 was expected to operate at a lower collision energy of 10 TeV but this was prevented by the 19 September 2008 shutdown. When at this target level, the LHC will have a significantly reduced luminosity, due to both fewer proton bunches in each beam and fewer protons per bunch. The reduced bunch frequency does allow the crossing angle to be reduced to zero however, as bunches are far enough spaced to prevent secondary collisions in the experimental beampipe.-->

=== Слой 1 — Трекер ===
<!--
Immediately around the interaction point the inner tracker serves to identify the tracks of individual particles and match them to the vertices from which they originated. The curvature of charged particle tracks in the magnetic field allows their charge and momentum to be measured.

The CMS silicon tracker consists of 13 layers in the central region and 14 layers in the endcaps. The innermost three layers (up to 11 cm radius) consist of 100 × 150 μm pixels, 66 million in total.

The next four layers (up to 55 cm radius) consist of 10 cm × 180 μm silicon strips, followed by the remaining six layers of 25 cm × 180 μm strips, out to a radius of 1.1 m. There are 9.6 million strip channels in total.

During full luminosity collisions the occupancy of the pixel layers per event is expected to be 0,1 %, and 1-2 % in the strip layers. The expected [[SLHC]] upgrade will increase the number of interactions to the point where over-occupancy may significantly reduce trackfinding effectiveness.

This part of the detector is the world’s largest silicon detector. It has 205 m² of silicon sensors (approximately the area of a tennis court) comprising 76 million channels.<ref>[http://cerncourier.com/cws/article/cern/32915 CMS installs the world’s largest silicon detector], CERN Courier, Feb 15, 2008</ref>-->

=== Слой 2 — Электромагнитный калориметр ===
<!--
The Electromagnetic Calorimeter (ECAL) is designed to measure with high accuracy the energies of [[electron]]s and [[photon]]s.

The ECAL is constructed from crystals of [[lead tungstate]], <math>PbWO_4</math>. This is an extremely dense but optically clear material, ideal for stopping high energy particles. It has a [[radiation length]] of <math>\chi_0=0.89cm</math>, and has a rapid light yield, with 80 % of light yield within one crossing time (25ns). This is balanced however by a relatively low light yield of 30 photons per MeV of incident energy.

The crystals used have a front size of 22×22 mm and a depth of 230 mm . They are set in a matrix of carbon fibre to keep them optically isolated, and backed by silicon [[avalanche photodiodes]] for readout. The barrel region consists of 61200 crystals, with a further 7324 in each of the endcaps.

At the endcaps the ECAL inner surface is covered by the Preshower subdetector, consisting of two layers of [[lead]] interleaved with two layers of silicon strip detectors. Its purpose is to aid in pion-photon discrimination.

<gallery widths="200px">
Image:CMS Silicon Tracker Arty HiRes.jpg|The silicon strip tracker of CMS
Image:Lead Tungstate Crystal Preparation.jpg|Preparing Lead Tungstate Crystals for the ECAL
</gallery>
-->

=== Слой 3 — Адронный калориметр ===
<!--[[Файл:CMS Hcal 26 01 2007.JPG|thumb|left|200px|Половина адронного калориметра]]
The purpose of the Hadronic Calorimeter (HCAL) is both to measure the energy of individual [[hadrons]] produced in each event, and to be as near to hermetic around the interaction region as possible to allow events with missing energy to be identified.

The HCAL consists of layers of dense material ([[brass]] or [[steel]]) interleaved with tiles of plastic [[Scintillation (physics)|scintillators]], read out via wavelength-shifting fibres by [[hybrid photodiodes]]. This combination was determined to allow the maximum amount of absorbing material inside of the magnet coil.

The high [[pseudorapidity]] region <math>(3.0<|\eta|<5.0)</math> is instrumented by the Hadronic Forward detector. Located 11m either side of the interaction point, this uses a slightly different technology of steel absorbers and quartz fibres for readout, designed to allow better separation of particles in the congested forward region.

The brass used in the endcaps of the HCAL used to be Russian artillery shells.<ref>[http://cmsinfo.cern.ch/outreach/CMStrivia/CMStrivia.html CMS trivia page — CERN]</ref>
-->

=== Слой 4 — Магнит ===
По состоянию на 2014 год магнит CMS — самый крупный из когда-либо созданных [[сверхпроводящий магнит|сверхпроводящих электромагнитов]]. Он создает магнитное поле 4 тесла внутри цилиндра диаметром 6 м и длиной 12,5 м. Ярмо магнита с массой около 10 тысяч тонн — самый тяжелый компонент детектора CMS.<ref>[http://cms-project-cmsinfo.web.cern.ch/cms-project-cmsinfo/Detector/Magnet/index.html Страница на сайте коллаборации]{{Недоступная ссылка|date=2018-02|bot=InternetArchiveBot }}</ref><ref>{{Cite web |url=http://elementy.ru/LHC/LHC/accelerator/detectors/CMS |title=Детектор CMS Магнит |lang=ru|access-date=2009-12-22 |archive-date=2010-03-11 |archive-url=https://web.archive.org/web/20100311034454/http://elementy.ru/LHC/LHC/accelerator/detectors/CMS |deadlink=no }}</ref>.
<!-- Like most particle physics detectors, CMS has a large [[solenoid]] magnet. This allows the charge/mass ratio of particles to be determined from the curved track that they follow in the magnetic field. It is 13 m long and 6 m in diameter, and its refrigerated superconducting niobium-titanium coils were originally intended to produce a 4 [[tesla (unit)|T]] magnetic field. It was recently announced that the magnet will run at 3.8 T instead of the full design strength in order to maximize longevity.{{Fact|date=April 2009}}

The inductance of the magnet is 14 [[henries|Η]] and the nominal current for 4 [[tesla (unit)|T]] is 19,500 [[ampere|A]], giving a total stored energy of 2.66 [[gigajoule|GJ]], equivalent to about half-a-tonne of [[Trinitrotoluene|TNT]]. There are dump circuits to safely dissipate this energy should the magnet [[Superconducting_magnet#Magnet_quench|quench]]. The circuit resistance (essentially just the cables from the power converter to the [[cryostat]]) has a value of 0.1 mΩ which leads to a circuit time constant of nearly 39 hours. This is the longest time constant of any circuit at CERN. The operating current for 3.8 [[tesla (unit)|T]] is 18,160 [[ampere|A]], giving a stored energy of 2.3 [[gigajoule|GJ]].
-->

=== Слой 5 — Мюонные детекторы и ярмо возврата ===
<!--To identify [[muon]]s and measure their momenta, CMS uses three types of detector: [[wire chamber|drift tubes]] (DT), [[cathode strip chambers]] (CSC) and [[resistive plate chambers]] (RPC). The DTs are used for precise trajectory measurements in the central ''barrel'' region, while the CSCs are used in the ''end caps''. The RPCs provide a fast signal when a muon passes through the muon detector, and are installed in both the barrel and the end caps.

<gallery widths="200px">
Image:HCAL Prepared for insertion.jpg|The Hadron Calorimeter Barrel (in the foreground, on the yellow frame) waits to be inserted into the superconducting magnet (the silver cylinder in the centre of the red magnet yoke).
Image:CMS Magnet barrel Ring with Muon chambers.jpg|A part of the Magnet Yoke, with drift tubes and resistive-plate chambers in the barrel region.
</gallery>
-->

== Сбор и обработка данных ==

=== Реконструкция ===
<!--[[Файл:Tracker FED Testing.jpg|thumb|right|200px|Testing the data read-out electronics for the tracker.]]
New particles discovered in CMS will be typically [[Particle decay|unstable]] and rapidly transform into a cascade of lighter, more stable and better understood particles. Particles travelling through CMS leave behind characteristic patterns, or ‘signatures’, in the different layers, allowing them to be identified. The presence (or not) of any new particles can then be inferred.-->

=== Триггерная система ===
<!-- To have a good chance of producing a rare particle, such as a [[Higgs boson]], a very large number of collisions are required. Most collision events in the detector are «soft» and do not produce interesting effects. The amount of raw data from each crossing is approximately 1MB, which at the 40MHz crossing rate would result in 40TB of data a second, an amount that the experiment cannot hope to store or even process properly. The trigger system reduces the rate of interesting events down to a manageable 100 per second.

To handle this, a series of «trigger» stages are employed. All the data from each crossing is held in buffers within the detector while a small amount of key information is used to perform a fast, approximate calculation to identify features of interest such as high energy jets, muons or missing energy. This «Level 1» calculation is completed in around <math>1\mu s</math>, and event rate is reduced by a factor of about thousand down to 50kHz. All these calculations are done on fast, custom hardware using reprogrammable [[FPGA]]s.

If an event is passed by the Level 1 trigger all the data still buffered in the detector is sent over [[fibre-optic]] links to the «High Level» trigger, which is software (mainly written in [[C++]]) running on ordinary computer servers. The lower event rate in the High Level trigger allows time for much more detailed analysis of the event to be done than in the Level 1 trigger. The High Level trigger reduces the event rate by a further factor of about a thousand down to around 100 events per second. These are then stored on tape for future analysis.
-->

=== Обработка данных ===
<!--Data that has passed the triggering stages and been stored on tape duplicated using the [[LHC Computing Grid|Grid]] to additional sites around the world for easier access and redundancy. Physicists are then able to use the Grid to access and run their analyses on the data.

Some possible analyses might be:
* Looking at events with large amounts of apparently missing energy, which implies the presence of particles that have passed through the detector without leaving a signature, such as [[neutrinos]].
* Looking at the [[kinematics]] of pairs of particles produced by the decay of a parent, such as the [[Z boson]] decaying to a pair of electrons or the [[Higgs boson]] decaying to a pair of [[tauon]]s or [[photons]], to determine the properties and mass of the parent.
* Looking at jets of particles to study the way the quarks in the collided protons have interacted.
-->

== Этапы строительства и запуска ==

{| class="wikitable" border="1"
|-
| 1998
| Начинается сооружение наземных зданий для CMS.
|-
| 2000
| Закрывается ускоритель LEP, начинается сооружение подземной полости.
|-
| 2004
| Завершено сооружение подземной полости.
|-
| 10 сентября 2008
| Первый протонный пучок в CMS.
|-
| 23 ноября 2009
| Первое столкновение протонных пучков в CMS.
|}
<gallery widths="200px">
|Введение вакуумного танка, июнь 2002 года
|Спуск YE+2 в полость CMS, декабрь 2006 года
|YE+1 - компонент CMS, весящий 1270 тонн, завершает спуск на 100 м в полость CMS, январь 2007
Image:Run62063ev2433.png|Компьютерное моделирование сброса пучка протонов на вольфрамовый блок вверх по пучку CMS в первый день работы ускорителя LHC, сентябрь 2008 года
</gallery>

== Примечания ==
{{примечания}}

{{навигация}}

== Ссылки ==
* [http://elementy.ru/LHC/LHC/accelerator/detectors/CMS Детектор CMS на сайте «Элементы»]
* [https://web.archive.org/web/20160304215739/http://www.poisknews.ru/2008/11/07/v_krugoverti_mikromira.html ''В круговерти микромира. Роль отечественных физиков'', Поиск, 07.11.2008.]
* [https://twitter.com/CMSexperiment CMS twitter с последними новостями CMS]
* [http://wayback.vefsafn.is/wayback/20081115135747/http://cms.cern.ch/ CMS home page]
* [http://cmsinfo.cern.ch/ CMS Outreach] {{Wayback|url=http://cmsinfo.cern.ch/ |date=20070316024214 }}
* [http://cmsinfo.cern.ch/outreach/CMSTimes.html CMS Times] {{Wayback|url=http://cmsinfo.cern.ch/outreach/CMSTimes.html |date=20080522094009 }}
* [https://web.archive.org/web/20120516122857/http://cmsinfo.jinr.ru/ Сайт проекта «Компактный мюонный соленоид» в Объединенном Институте Ядерных Исследований (ОИЯИ, г. Дубна)]
* [https://web.archive.org/web/20070709094254/http://www.petermccready.com/portfolio/07041601.html https://web.archive.org/web/20070709094254/http://www.petermccready.com/portfolio/07041601.html] Panoramic view — click and drag to look around the experiment under construction (with sound!) (requires Quicktime)
* [https://www.youtube.com/watch?v=7FiLC2m4oR8 The assembly of the CMS detector, step by step, through a 3D animation]
* {{Citation |title=The CMS experiment at the CERN LHC |url=http://www.iop.org/EJ/journal/-page=extra.lhc/jinst |author=The CMS Collaboration, S Chatrchyan ''et al'' |journal=Journal of Instrumentation |date=2008-08-14 |volume=3 |doi=10.1088/1748-0221/3/08/S08004 |accessdate=2008-08-26 |pages=S08004}} (Full design documentation)
* [https://web.archive.org/web/20170414163949/https://lhip.nsu.ru/%d0%b3%d0%bb%d0%b0%d0%b2%d0%bd%d0%b0%d1%8f Лаборатория физики адронных взаимодействий НГУ]

{{CERN}}

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[[Категория:Экспериментальные установки физики элементарных частиц]]
[[Категория:Большой адронный коллайдер]]