Abstract
The Compact Muon Solenoid CMS operates at the Large Hadron Collider LHC at CERN.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
Prior to this meeting about 70 \(\mathrm{m}^{2}\) silicon plus \(\sim \)200 \(\mathrm{m}^{2}\) MicroStrip Gas Chamber MSGC were specified in the initial Technical Design Report TDR [290].
- 2.
It was 3 barrel layers and 2 forward disks from 2008 to 2016.
- 3.
Analogue data represents pulse height to allow a centre-of-charge analysis later.
- 4.
Installation of the beam pipe requires a high temperature bake-out to allow a good final vacuum which takes several weeks.
- 5.
New outer diameter D \(=45\) mm with respect to old D \(=59.6\) mm.
- 6.
New cooling pipes, compatible with the high pressures of a CO\(_2\) cooling system (triple vacuum jacketed steal pipes) have been installed during long shutdown 1; two years in advance of the pixel installation.
- 7.
A buck converter is a voltage step down converter. It is a switching converter storing the energy in an inductor. Due the CMS magnetic field only air coils can be used.
- 8.
100 Hz HLT rate is the original design, today 1 kHz rate is standard while several kHz can be stored for dedicated calibration studies, e.g. timing scans.
- 9.
Reminder: fluence numbers are always given in 1 MeV neutron equivalent/\(\mathrm{cm}^{2} [\varPhi _{eq}]=n_{1\, \mathrm{MeV}}/\mathrm{cm}^{2}\).
- 10.
At a feature size of 0.25 \(\upmu \)m and below, chips start to be enough radiation tolerant for LHC operation.
- 11.
Another radiation-tolerant technology called DMILL existed but there were some production yield problems.
- 12.
0.25 \(\upmu \)m version of the APV chip – final version.
- 13.
With an initially lower luminosity an integral fluence of \(\varPhi _{eq }=6\cdot 10^{14}~n_{1\, \mathrm{MeV}}/\mathrm{cm}^{2\, }\) was expected after 4 – 5 years of initial running.
- 14.
In n-in-n under-depletion mode, the non-depleted zone stays on the backside only reducing the active volume but with depletion zone at the segmented pixel face.
- 15.
GND potential is finally connected via the individual chip cells but for sensor testing purposes a bias grid has been implemented.
- 16.
- 17.
Main field from the high bias voltage applied to reverse bias the pn-junction.
- 18.
Proportional plus Integral plus Derivative PID control, an industry control standard.
- 19.
Today 2017, there are 69 Tracker Institutes.
- 20.
During operation together with the hybrid, the potential on the chip connections are \(+\)0.85 V higher than the sensor ground.
- 21.
Until 2017, an additional C\(_6\)F\(_{14}\) one was serving 18 lines for the pixel detector but has been replaced with a CO\(_2\) system for the Pixel Phase I detector. The CO\(_2\) is situated in the service cavern and has only dedicated passive manifolds on the experimental cavern.
- 22.
In CMS magnetic fringe field and radiation environment; with about 60 m long transfer lines.
- 23.
C\(_6\)F\(_{14}\) is much denser/heavier than water.
- 24.
Pipes had been closed on both sides with the liquid not yet thermalised to room temperature thus pressure increased during warm up. Later the possibility to close the return end was abandoned.
- 25.
With 180 pipes in a very small and thus crowded environment, thermal insulation was not possible.
- 26.
Several hundreds of temperature and dew point sensors have been installed to have good local understanding of the environment; something missing during RUN I.
- 27.
Most often called sniffer pipes.
- 28.
System reducing the oxygen content in air to a non-flammable value, often used in oil tankers to inert the environment preventing fire.
- 29.
Two individuals took 14 h-shifts at the experiment seven days a week for 6 weeks.
- 30.
Design was 100 Hz, since 2012 more than 1 kHz events of data are being saved.
- 31.
DCU; situated on each hybrid, the DCU measures temperatures of hybrid and sensor, several voltages plus the sensor leakage current.
- 32.
It showed that a gain per individual channel was not necessary.
- 33.
It should be mentioned that the LHC is performing much better than the design specification – about twice in 2017.
- 34.
Minimum Bias MB events with inelastic scattering but minimum detector activity, not the high momentum or high multiplicity part, a special MB trigger exist.
- 35.
One extreme example: in 2015, one pixel forward detector was globally located 3 – 5 mm away from its foreseen place, given that it was not properly fixed and the final cable connection pulled it slightly. This was full recognised and mitigated by software alignment.
- 36.
Kalman Filters have a broad use-case namely navigation, radar tracking, stock market prediction. Deviations as from wind, money exchange rates, multiple scattering can be processed as stochastic noise.
- 37.
With a pile-up of PU = 25 one has about \(10^{9}\) interactions every second.
- 38.
192 cells times 25 ns.
- 39.
Except for electrons – Bremsstrahlung.
- 40.
Worth to note: Since 2017 with the phase I pixel detector, the pixel seeding is composed of quadruplets with triplets as backup instead of triplets with pairs as backup.
- 41.
E.g. TOB has 2 modules and each TOB sensor is 5/3 times thicker than a TIB sensor.
- 42.
A moderator has been installed instrumented between endap calorimeter and Tracker to limit the neutron exposure.
- 43.
The extracted pixel detector was still kept cold most of the LS1 period.
- 44.
For the simulation the temperature is only taken into account 2 times per day thus the simulated currents (blue) do not follow here.
- 45.
The CMS data during a full scan is not useful for physics analyses; during a small scan it is.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2017 Springer International Publishing AG
About this chapter
Cite this chapter
Hartmann, F. (2017). CMS: Increasing Size by 2 Orders of Magnitude. In: Evolution of Silicon Sensor Technology in Particle Physics. Springer Tracts in Modern Physics, vol 275. Springer, Cham. https://doi.org/10.1007/978-3-319-64436-3_6
Download citation
DOI: https://doi.org/10.1007/978-3-319-64436-3_6
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-64434-9
Online ISBN: 978-3-319-64436-3
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)