the btev experiment: physics and detector fpcp 2003 k. honscheid ohio state university
DESCRIPTION
The BTeV Experiment: Physics and Detector FPCP 2003 K. Honscheid Ohio State University. More details can be found at www-physics.mps.ohio-state.edu/~klaus/research/cipanp.pdf and the BTeV web site at fnal.gov. B Physics Today. CKM Picture okay CP Violation observed No conflict with SM. - PowerPoint PPT PresentationTRANSCRIPT
FPCP 2003K. HonscheidOhio State
The BTeV Experiment:Physics and Detector
FPCP 2003K. Honscheid
Ohio State University
More details can be found atwww-physics.mps.ohio-state.edu/~klaus/research/cipanp.pdf andthe BTeV web site at fnal.gov
FPCP 2003K. HonscheidOhio State
B Physics Today
CKM Picture okay
CP Violation observed
No conflict with SM
Vud Vus Vub
VCKM = Vcd Vcs Vcb
Vtd Vts Vtb
sin(2) = 0.734 +/- 0.054
>1011 b hadrons
(including Bs)
FPCP 2003K. HonscheidOhio State
B Physics at Hadron Colliders
Energy 2 TeV 14 TeVb cross section ~100 b ~500 b
c cross section ~1000 b ~3500 bb fraction 2x10-3 6x10-3
Inst. Luminosity 2x1032 >2x1032
Bunch spacing 132 ns (396 ns) 25 nsInt./crossing <2> (<6>) <1>Luminous region 30 cm 5.3 cm
Tevatron LHC
Large cross sectionsTriggering is an issueAll b-hadrons produced (B, Bs, Bc, b-baryons)
FPCP 2003K. HonscheidOhio State
Detector Requirements
From F. Teubert
•Trigger, trigger, trigger •Vertex, decay distance•Momentum•PID•Neutrals (, 0)
FPCP 2003K. HonscheidOhio State
Forward vs. Central Geometry
b production angle
b production angle
230b
100b
Multi-purpose experiments requirelarge solid angle coverage.
Central Geometry (CDF, D0, Atlas, CMS)
Dedicated B experiments can takeadvantage of
Forward geometry(BTeV, LHCb)
FPCP 2003K. HonscheidOhio State
The BTeV Detector
Beam Line
FPCP 2003K. HonscheidOhio State
Pixel Vertex Detector
Reasons for Pixel Detector:• Superior signal to noise• Excellent spatial resolution -- 5-10 microns depending on angle, etc• Very Low occupancy• Very fast • Radiation hardSpecial features:• It is used directly in the L1 trigger• Pulse height is measured on every channel with a 3 bit FADC• It is inside a dipole and gives a crude standalone momentum
Doublet
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The Pixel Detector II
Vacuum System
FPCP 2003K. HonscheidOhio State
Simulated B Bbar, Pixel Vertex Detector
FPCP 2003K. HonscheidOhio State
Level 1 vertex trigger architecture
FPGA segment trackers
Merge
Trigger decision to Global Level 1
Switch: sort by crossing number
track/vertex farm(~2500 processors)
30 station pixel detector
FPCP 2003K. HonscheidOhio State
Generate Level-1 accept if “detached” tracks in the BTeV pixel detector satisfy:
2
2.0
25.02
b
mb
pT
(GeV/c)2
cm
L1 vertex trigger algorithm
b
p p
B-meson
FPCP 2003K. HonscheidOhio State
Efficiencies and Tagging
For a requirement of at least 2 tracks detached by more than 6, we trigger on only 1% of the beam crossings and achieve the following trigger efficiencies for these states (<2> int. per crossing):
Decay efficiency(%) Decay efficiency(%)
B +- 63 Bo K+- 63
Bs DsK 74 Bo J/ Ks 50
B- DoK- 70 Bs J/K* 68
B- Ks- 27 Bo K*
74%
1%
Impact Parameter in units of Impact Parameter in units of
Trigger Efficiency-Minimum Bias EventsTrigger EfficiencyBsDsKE
F
F
I
C
I
E
N
C
Y
E
F
F
I
C
I
E
N
C
Y
N=1
N=2
N=3
N=4
N=1
N=2
N=3
N=4
FPCP 2003K. HonscheidOhio State
The Physics Goals
There is New Physics out there: Baryon Asymmetry of Universe & by Dark MatterHierarchy problemPlethora of fundamental parameters…
B Experiments at Hadron Colliders are well positioned to:
Perform precision measurements of CKM Elements withsmall model dependence.Search for New Physics via CP phasesSearch for New Physics via Rare DecaysHelp interpret new results found elsewhere (LHC, neutrinos)Complete a broad program in heavy flavor physics
Weak decay processes, B’s, polarization, Dalitz plots, QCD…
Semileptonic decays including b
b & c quark ProductionStructure: B(s) spetroscopy, b-baryon statesBc decays
FPCP 2003K. HonscheidOhio State
Importance of Particle Identification
BTeV RICH Detector
Gas
Liquid
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Measuring Using Bo
A Dalitz Plot analysis gives both sin(2) and cos(2)(Snyder & Quinn)
Measured branching ratios are:
(B = ~10-5
(B + = ~3x10-5
(B <0.5x10-5
Snyder & Quinn showed that 1000-2000 tagged events are sufficient
Not easy to measure0 reconstruction
Not easy to analyze9 parameter likelihood fit
Slow 0’s
Nearly empty( polarization)
Dalitz Plot for Bo
FPCP 2003K. HonscheidOhio State
Yields for BoBased 9.9x106 background events
Bo+-
5400 events, S/B = 4.1
Booo
780 events, S/B = 0.3
o
Background Signal
mB (GeV) mB (GeV)
Booo
FPCP 2003K. HonscheidOhio State
Our Estimate of Accuracy on
Geant simulation of Bo(for 1.4x107 s)
Example:1000 Bo signal + backgroundsWith input =77.3o
minimum 2
non-resonantnon- bkgrd
resonantnon- bkgrd
(gen)
Rres Rnon(recon)
77.3o 0.2 0.2 77.2o 1.6o
77.3o 0.4 0 77.1o 1.8o
93.0o 0.2 0.2 93.3o 1.9o
93.0o 0.4 0 93.3o 2.1o
111.0o 0.2 0.2 111.7o 3.9o
111.0o 0.4 0.2 110.4o 4.3o
FPCP 2003K. HonscheidOhio State
Electromagnetic CalorimeterThe main challenges include
• Can the detector survive the high radiation environment ?• Can the detector handle the rate and occupancy ?• Can the detector achieve adequate angle and energy resolution ?BTeV will have a high resolution PbWO4 calorimeter• Developed by CMS for use at the LHC• Large granularity
Block size 2.7 x 2.7 x 22 cm3 (25 Xo)~11000 crystals
• Photomultiplier readout (no magnetic field)• Pre-amp based on QIE chip (KTeV)• Energy resolution
Stochastic term 1.8%Constant term 0.55%
• Position resolution E
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FPCP 2003K. HonscheidOhio State
Electromagnetic Calorimeter Tests
Block from China’s Shanghai Institute
• Resolution (energy and position) close to expectations
• This system can achieve CLEO/BaBar/BELLE-like performance in a hadron Collider environment!
FPCP 2003K. HonscheidOhio State
Rare b Decays Search for New Physics in Loop diagrams
New fermion like objects in addition to t, c or uNew Gauge-like objects in addition to W, Z or g
Inclusive Rare Decays including bs bd bs+
Exclusive Rare Decays such as BBK*+ Dalitz plot & polarization
+-
BoK*
FPCP 2003K. HonscheidOhio State
BTeV data compared to Burdman et al calculation
Dilepton invariant mass distributions,forward-backward asymmetrydiscriminate among the SM and various supersymmetric theories.(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)
One year for K*+-, enough to determine if New Physics is present
Polarization in BoK*o+-
Ali et. al, hep-ph/9910221
FPCP 2003K. HonscheidOhio State
Muon System
track from IP
toroid(s) / iron
~3 m
2.4 m halfheight
Provides Muon ID and TriggerTrigger for interesting physics statesCheck/debug pixel trigger
fine-grained tracking + toroid
Stand-alone mom./mass trig.Momentum “confirmation”
Basic building block: Proportional tube “Planks”
FPCP 2003K. HonscheidOhio State
Summary
Heavy quark physics at hadron colliders provides a unique opportunity to
measure fundamental parameters of the Standard Model with no or only small model dependencediscover new physics in CP violating amplitudes or rare decays.interpret new phenomena found elsewhere (e.g. LHC)
Some scenarios are clear others will be a surprise
This program requires a general purpose detector like BTeV with
an efficient, unbiased trigger and a high performance DAQa superb charged particle tracking systemgood particle identificationexcellent photon detection
FPCP 2003K. HonscheidOhio State
Additional Transparencies
FPCP 2003K. HonscheidOhio State
Physics Reach (CKM) in 107 s Reaction B(B)
(x10-6)# of Events
S/B Parameter Error or (Value)
Bs Ds K- 300 7500 7 - 8o
Bs Ds- 3000 59,000 3 xs (75)
BoJ/KS J/+ - 445 168,000 10 sin(2) 0.017
BoJ/Ko, Ko 7 250 2.3 cos(2) ~0.5
B-Do (K+-) K- 0.17
170 1
B-Do (K+K-) K- 1.1 1,000 >10 13o
BsJ/ 330 2,800 15
BsJ/ 670 9,800 30 sin(2 0.024
Bo+- 28 5,400 4.1
Booo 5 780 0.3 ~4o Reaction B(B)
(x10-6)# of Events
S/B Parameter Error
B-KS -
12.1 4,600 1 <4o +
BoK+- 18.8
62,100 20 Theory err.
Bo+- 4.5 14,600 3 Asymmetry 0.030
BoK+ K- 17 18,900 6.6 Asymmetry 0.020
FPCP 2003K. HonscheidOhio State
A simplified trigger comparison
From U. Egede
FPCP 2003K. HonscheidOhio State
Unitarity TrianglesUnitarity Triangles
Bd0
Bd0
Bd0 DK*0
BS0 DSK
Bd0 D*
BS0 DS
Bd0 J/ KS
0
BS0 J/
From N. Harnew
FPCP 2003K. HonscheidOhio State
Pixel Test Beam Results
Track angle (mr)
No changeafter 33 Mrad(10 years, worst case, BTeV)
Analog output of pixel amplifier before and after 33 Mrad irradiation.0.25 CMOS design verified radiationhard with both and protons.
FPCP 2003K. HonscheidOhio State
Forward Tracker
Predicted performance -Momentum resolution is better than 1% over full momentum and angle range
Prototype Straw tracker being constructed for FNALbeam test summer/fall 2002
DrawingOf forwardMicrostriptracker
FPCP 2003K. HonscheidOhio State
HPD Schematic for BTeV RICH
HPD Tube HPD Pixel array HPD Pinout
Pulse Height from163 pixel prototypeHPD. Note pedestal,1, 2, 3 pe peaks
FPCP 2003K. HonscheidOhio State
Prop Tube Planks
3/8” diameter Stainless steel tubes (0.01” walls)“picket fence” design 30 (diameter) gold-plated tungsten wireManifolds are brass soldered to tubes (RF sheilding important!)Front-end electronics: use Penn ASDQ chips, modified CDF COT cardTry “D0 fast gas” 88% Ar - 10% CF4 - CO2 or 50% Ar – 50% Eth.
Basic Building Block: Proportional Tube “Planks”
FPCP 2003K. HonscheidOhio State
Plank Cosmic Ray Tests
Cosmic Ray Test Stand
FPCP 2003K. HonscheidOhio State
BTeV Data Acquisition Architecture
B TeV d etec to r
L 1 m uon
L 1 vertex
G loba lL evel-1
L eve l-1
L ev el 2 /3 C ro ss in g S w itch
D a ta L o g g in g
F ron t-end e lec tron ics
L eve l-1 B uffe rs
L eve l-2 /3 B uffe rs
I n f o r m a tio n T r a n s fe r C o n t r o l H a r d w a r e
IT C H
L eve l-2 /3 P rocessor F a rm
#1
#2
#m -1
#m
RDY
Crossing #N
Req. data for crossing #N
L eve l-3 accep t
G L 1 accep t
P IX
> 2 x 10 channe ls7
800 GB/s7.6 MHz
L1 rate reduction: ~1/100
L2/3 rate reduction: ~1/20
4 KHz 200 MB/s
FPCP 2003K. HonscheidOhio State
PbWO4 Calorimeter Properties
Property ValueDensity(gm/cm2) 8.28Radiation Length(cm) 0.89Interaction Length(cm) 22.4Light Decay time(ns) 5(39%) (3components) 15(60%)
100(1%)Refractive index 2.30Max of light emission 440nmTemperature Coefficient (%/oC) -2Light output/Na(Tl)(%) 1.3Light output(pe/MeV) into 2” PMT 10
Property ValueTransverse block size 2.7cm X 2.7 cmBlock Length 22 cmRadiation Length 25Front end Electronics PMTInner dimension +/-9.8cm (X,Y)Energy Resolution: Stochastic term 1.8% (2.3%) Constant term 0.55%Spatial Resolution: Outer Radius 140 cm--215 cm
$ drivenTotal Blocks/arm 11,500
Ex
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