Download What is new at CERN? - Vanderbilt HEP

Compact Muon Solenoid (CMS) Physics,
Status, and Plans
Bill Gabella and Med Webster
QuarkNet 2013
Vanderbilt University
Outline
–
–
–
–
–
–
8 July 2013
The Standard Model of Particle Physics
The Large Hadron Collider
The Compact Muon Solenoid
Proton on Proton collisions
● Higgs Boson, now your run-of-the-mill Standard Model Higgs
● Supersymmetry, NOT?
● Extra Dimensions
Lead on Lead collisions
● centrality, Jet Quenching
● ridge in two particle correlations
Large Hadron Collider and CMS plans
Gabella CMS Status
2
Particle Physics,
aka High-Energy Physics,
aka Theory of Fundamental Particles
All stable matter is made
of protons, neutrons, and
electrons.
Yes, but protons and
neutrons are also made
up of Quarks!
8 July 2013
Gabella CMS Status
3
The Standard Model
A good description of fundamental particle interactions, relevant inside the
nucleus, at early times in the evolution of the universe, and in man-made
and natural collisions of particles.
Particles that “carry” the force.
Particles that make up Matter.
All of the matter and forces in the Universe are made up of:
6 leptons (and 6 anti-leptons), 6 quarks (and 6 anti-quarks), and 12 force carrying
particles...ur plus the Higgs boson and don't forget Gravity, and...
8 July 2013
Gabella CMS Status
4
8 July 2013
Gabella CMS Status
5
Ref: http://www.particleadventure.org
8 July 2013
Gabella CMS Status
6
Cosmic Ray
Showers
Mostly Protons with
high energy hitting
the atmosphere...
make mostly muons
at Earth.
Ref: http://www.particleadventure.org
8 July 2013
Gabella CMS Status
7
Particle Accelerators
Large Hadron Collider, p on p
Geneva, Switzerland
7, 8, and soon 14 TeV
center of mass
Tevatron, was p on p-bar
Batavia, IL (Chicago)
2 TeV center of mass
now lower energy, high intensity p
source, also intense neutrino source
8 July 2013
Gabella CMS Status
Ref: www.fnal.gov, www.cern.ch
8
The Large Hadron Collider
Proton-on-Proton collider, 2010-11 3.5+3.5 TeV center of mass energy
2012
4+4 TeV
plan 2015
7+7 TeV
also Lead-on-Lead (aka Heavy Ion) collider
and Proton-on-Lead for comparison of the above two
8 July 2013
Gabella CMS Status
9
The Large Hadron Collider
8 July 2013
Gabella CMS Status
10
The Large Hadron Collider
8 July 2013
Gabella CMS Status
11
Large Hadron Collider (LHC)
Energies:
Linac 50 MeV
PSB
1.4 GeV
PS
28 GeV
SPS 450 GeV
LHC 3.5, 4, 7 TeV
8 July 2013
Ref: Introduction to Accelerators,
Wildner, CERN
Gabella CMS Status Elena
12
CMS Detector
Vanderbilt University (Will Johns)
8 July 2013
Gabella CMS Status
http://www.uscms.org/public_2/about/cms_detector/index.shtml
13
Particles through a CMS slice
8 July 2013
Gabella CMS Status
14
The Forward and Barrel Pixel Detector
Barrel Pixel
r = 4.4, 7.3, and 10.2 cm
11520 readout chips, 48 Mpixels
Forward Pixel
z = +/-34.5, and +/-46.5 cm
4320 readout chips, 18 Mpixels
8 July 2013
Gabella CMS Status
http://www.hep.vanderbilt.edu/
15
borrowed from Mauro Dinardo docdb 2404
CMS - Short Timeline
March 2010 --- Started taking data on collisions at 7 TeV. Previous testing
done at 0.45 TeV (injection energy) and 1.26 TeV. Low
luminosity (intensity)
2010 - 2011 --- Taking data with increasing luminosity (intensity) by both
more proton bunches in the rings and more protons in
each bunch
2012
--- Running at 8 TeV, and high luminosity
July 4, 2012 --- Announce discovery of Higgs-like particle, also seen with
the ATLAS detector
March 2013 --- Shutdown LHC and detectors for “Long Shutdown 1,”
aka LS1. LHC back “on” in 2015 with energy 14 TeV.
8 July 2013
Gabella CMS Status
16
CMS Recent Results - Higgs
July 4, 2012 --- CMS and ATLAS report “Higgs-like particle” at 125 GeV.
Too many H->Gamma Gamma events compared to the
Standard Model predictions for the Higgs.
July 4, 2013 --- The Higgs looks a lot like the Standard Model (SM) Higgs.
Right ratio of different events, better statistics.
Mass 125.8 GeV +/- 0.5 GeV
Now measuring the quantum numbers of the Higgs:
consistent with spin 0 (at least not spin 1 nor spin 2);
parity consistent with +1
8 July 2013
Gabella CMS Status
17
8 July 2013
Gabella CMS Status
18
Higgs decays into...
8 July 2013
Gabella CMS Status
19
Higgs to two Z's to Four Leptons
8 July 2013
Gabella CMS Status
borrowing from Higgs Seminar
20
Note the numbers...
Black dots are data.
8 July 2013
Gabella CMS Status
21
CMS (Some) Other Important Results
●
●
Supersymmetry
–
Looking for “missing energy,” i.e. invisible particles,
at least to the detector, as are neutrinos.
–
Currently appears to have eliminated many popular
SUSY models; we are left with the 105 parameter
full-model (maybe).
Extra-dimensions
–
Inspired by Super-strings, Randall and Sundrum
took the idea of extra-dimensions (spatial) seriously
and asked what would accelerators see/measure.
No discovery, putting
limits
on the models.
Gabella
CMS Status
–
8 July 2013
22
CMS Heavy Ion Collisions
●
LHC Collides Pb-208 ions, fully-stripped to +82 charge
–
●
●
in other words, atomic number Z=82, atomic mass
A=208, number of neutrons N=126
For protons we inject at 450 GeV and ramp up to 3.5 TeV
Acceleration is by electric field, so a charged particle with
charge Ze would be injected at 450 Z GeV and ramp to
3.5 Z TeV total energy.
–
The bending magnets determine what energy (really
momentum!) that you can have in your ring of radius
rho.
8 July 2013
Gabella CMS Status
23
CMS Heavy Ion Collisions
p on p
3.5 + 3.5 TeV
Pb on Pb
287 + 287 TeV 1.38 + 1.38 TeV
7 TeV c.o.m.
p on p
4 + 4 TeV
2.76 TeV/u
Pb on Pb
328 + 328 TeV 1.577 + 1.577 TeV
8 TeV c.o.m.
p on Pb
8 July 2013
3.15 TeV/u (??)
4 + 328 TeV
4 + 1.577 TeV/u
just nucleons
5.02 TeV c.o.m.
boosted!
not at rest!
Gabella CMS Status
24
CMS Heavy Ions, some numbers
Pb-208 accounts for 52.4% of all stable lead.
Z=82, N=126, A=208
8 July 2013
Gabella CMS Status
25
CMS Heavy Ions - A tutorial
well centered or glancing
blow = Centrality
8 July 2013
Gabella CMS Status
26
CMS Heavy Ions - Make a lot of Particles!
8 July 2013
Gabella CMS Status
27
CMS Heavy Ions - Jet Quenching
Main Jet - not modified
In a head-on collision, more Jets
(q-qbar hadron shower) near the
edge of the fireball.
Borrowed from Iancu fig 42.
8 July 2013
Gabella CMS Status
Away Jet - highly modified
28
CMS Heavy Ions - Jet Quenching
Main Jet - not modified
Away Jet - highly modified
8 July 2013
Gabella CMS Status
29
LHC and CMS Plans
Currently the LHC and all the experiments are doing maintenance.
Expect to start turning on the LHC in 2015, with data taking my
mid-year.
8 July 2013
Gabella CMS Status
30
LHC and CMS Plans
8 July 2013
Gabella CMS Status
31
Backup
8 July 2013
Gabella CMS Status
32
Some Links/References
The Standard Model of Particle Physics
●
http://www.particleadventure.org
●
Vanderbilt HEP Group http://www.hep.vanderbilt.edu/~focuser/index.php
●
CMS Public Talks http://cms.web.cern.ch/org/cms-presentations-public
●
CMS News http://cms.web.cern.ch
LHC and Heavy Ions
●
●
Ions Page
http://lhc-commissioning.web.cern.ch/lhc-commissioning/commissioning-ions.htm
http://lhc-commissioning.web.cern/lhc-commissioning/commissioning-ions.htm
LHC consolidations
http://home.web.cern.ch/about/accelerators/large-hadron-collider
http://home.web.cern.ch/about/updates/2013/03/lhc-consolidations-step-step-guide
8 July 2013
Gabella CMS Status
33
Backup
8 July 2013
Gabella CMS Status
34
Units? 1 eV...
8 July 2013
Gabella CMS Status
35
8 July 2013
Gabella CMS Status
36
LHC Ions, the Numbers 1/4
●
LHC Collides Pb-208 ions, fully-stripped to +82 charge
–
●
●
in other words, atomic number Z=82, atomic mass
A=208
For protons we inject at 450 GeV and ramp up to 3.5 TeV
Acceleration is by electric field, so a charged particle with
charge Ze could be injected at 450 Z GeV and ramp to 3.5
Z TeV.
–
The bending magnets determine what energy (really
momentum!) that you can have in your ring.
8 July 2013
Gabella CMS Status
37
LHC Ions, the Numbers 2/4
●
A magnetic field B bends a charged particle with
momentum P in an arc of radius
.
–
Magnet folks like the constant "magnetic rigidity"
–
For the LHC ring (and the other injector rings), the B is
set by power supplies and magnets and the rho by the
vacuum pipe
8 July 2013
Gabella CMS Status
38
LHC Ions, the Numbers 3/4
–
So you will see people post that we are injecting at
450 Z GeV and ramping to 3.5 Z TeV for each Pb
nucleus (which is a lot, 36.9 TeV injection and ramp to
287 TeV)
–
Okay for the physics what is more interesting is the
per proton/neutron energy, so per nucleon the
numbers are less
450 Z/A GeV and ramp to 3.5 Z/A TeV
–
Z/A is the average charge per nucleon, 0.4 e, and
finally, inject at 177 GeV/u ramp to 1.38 TeV/u, and
collide at 2.76 TeV/u.
8 July 2013
Gabella CMS Status
39
LHC Ions, the Numbers 4/4
●
Bunch populations, from recent posting,
–
per bunch charge of 1-1.2e10 ... e's
–
Count the Pb ions at +82e each, find there are
12-14e7 Pb ions per bunch (below you will see that
7e7 is the design)
8 July 2013
Gabella CMS Status
40
LHC Ions Injection Chain
8 July 2013
Gabella CMS Status
41
Pixel Numerology
●
Barrel has 11520 ROCs, 48 MPxl
●
Forward has 4320 ROCs, 18 MPxl
●
1 ROC has 4160 pixels
●
Si Sensor pixel size is 100 microns by 150 microns
●
●
Fpix has 3 plaquette and 4 plaquette config to its panels: 3
plaquette: 2x5 + 2x4 + 2x3 (ROCs), and the 4 plaquette:
1x5 + 2x4 + 2x3 + 1x2 (ROCs)
Urs shows fpix: (3x24+3x21)/4320 = 2.6% and bpix
(3x16+6x8+3)/1152 = 0.9% not working.
8 July 2013
Gabella CMS Status
42
LHC Ions Physics "Trivia"
●
●
●
8 July 2013
Luminosity is limited by the Electron Capture by Pair
Production (ECPP) at the IPs. That is, the e- from an e+e- pair
produced in the collision is captured by an Pb ion and that ion
is lost on collimators leading to a vacuum problem! Limit is
0.5-1e27 cm^-2 s^-1.
Original choice was Pb+53 after the first foil into LEAR. It was
found that it had an unexpected short lifetime in the electron
cooler, it picked up an e- in a much shorter time than either
Pb+52 or +54. Chose +54 state. Pb+53 ends with a 5p^5
orbital---that looks bad!
While Pb+52 ends with 5p^4 (all paired) and +54 ends with
5p^6.
Beam Loss Induced Vacuum degradation in LEAR, and the
creation of other charge states by Pb+54 interacting with the
beam gas, led to a vacuum spec in LEAR of
1e-12 mbar (LHC can be 1e-9mbar).
Gabella CMS Status
43
The Standard Model - The Tee Shirt
8 July 2013
Gabella CMS Status
44
The Standard Model - The Details
A pretty equation for the Lagrangian Density of the quantum fields...
Photons, W's, Z's bosons, gluons
Electrons, Quarks, Neutrinos
Higgs “coupled” to leptons
Higgs Particle/Field
8 July 2013
Gabella CMS Status
45
“ In its most explicit form, the Lagranian density of the minimal Standard Model
is given by the somewhat uninspiring expression:” A. Connes & M. Marcolli
gluons
photons
W's and Z's
8 July 2013
Gabella CMS Status
46
Higgs Particle/Field
8 July 2013
Gabella CMS Status
47
The
Standard
Model
The
Details
...there is more...
electrons
up quarks
8 July 2013
Gabella CMS Status
48
CMS Detector
“ In its most explicit form, the Lagranian density of the minimal Standard Model
is given by the somewhat uninspiring expression:” A. Connes & M. Marcolli
Electromagnetic Fields, W's, Z's bosons
Electrons, Quarks, Neutrinos
Higgs Particle/Field
8 July 2013
Gabella CMS Status
49
An Event: Higgs to 4 muons
8 July 2013
Gabella CMS Status
http://www.uscms.org/public_2/about/cms_detector/index.shtml
50
An Event: Higgs to 4 muons
8 July 2013
Gabella CMS Status
51