The BTeV Experiment: Physics and Detector
FPCP 2003 K. Honscheid Ohio State University
FPCP 2003 K. Honscheid Ohio State B Physics Today
CKM Picture okay
Vud Vus Vub
VCKM = Vcd Vcs Vcb
Vtd Vts Vtb
CP Violation observed
sin(2b) = 0.734 +/- 0.054 >1011 b hadrons
No conflict with SM (including Bs)
FPCP 2003 K. Honscheid Ohio State B Physics at Hadron Colliders
Tevatron LHC Energy 2 TeV 14 TeV b cross section ~100 mb ~500 mb c cross section ~1000 mb ~3500 mb b fraction 2x10-3 6x10-3 Inst. Luminosity 2x1032 >2x1032 Bunch spacing 132 ns (396 ns) 25 ns Int./crossing <2> (<6>) <1> Luminous region 30 cm 5.3 cm
Large cross sections Triggering is an issue
All b-hadrons produced (B, Bs, Bc, b-baryons) FPCP 2003 K. Honscheid Ohio State Detector Requirements
•Trigger, trigger, trigger •Vertex, decay distance •Momentum •PID FPCP 2003 K. Honscheid 0 Ohio State •Neutrals (g, p ) From F. Teubert Forward vs. Central Geometry
Multi-purpose experiments require large solid angle coverage. Central Geometry (CDF, D0, Atlas, CMS) 100mb Dedicated B experiments can take 230mb advantage of Forward geometry (BTeV, LHCb)
bg
b production angle
FPCP 2003 K. Honscheid b production angle Ohio State The BTeV Detector
Beam Line
FPCP 2003 K. Honscheid Ohio 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 hard
Special 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
FPCP 2003 K. Honscheid Ohio State The Pixel Detector II
Vacuum System
FPCP 2003 K. Honscheid Ohio State Simulated B Bbar, Pixel Vertex Detector
FPCP 2003 K. Honscheid Ohio State L1 vertex trigger algorithm
Generate Level-1 accept if ³ 2 “detached” tracks in the BTeV pixel detector satisfy:
2 (GeV/c)2 pT ³0.25 b³ms b£0.2 cm B-meson
p p
b
FPCP 2003 K. Honscheid Ohio State Level 1 vertex trigger architecture
30 station pixel detector
FPGA segment trackers
Switch: sort by crossing number
track/vertex farm (~2500 processors)
Merge
Trigger decision to Global Level 1
FPCP 2003 K. Honscheid Ohio State Efficiencies and Tagging Trigger Efficiency-Minimum Bias Events Trigger EfficiencyBsàDsK E E N=1 F F N=1 F F I 74% I N=2 N=2 C C I I N=3 E E 1% N=3 N N=4 N C C N=4 Y Y Impact Parameter in units of s Impact Parameter in units of s For a requirement of at least 2 tracks detached by more than 6s, 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 ® p+p- 63 Bo ® K+p- 63 o Bs ® DsK 74 B ® J/y Ks 50 - o - * B ® D K 70 Bs ® J/yK 68 - - o * FPCP 2003 B ® K p 27 B ® K g 40 K. Honscheid s Ohio State The Physics Goals
There is New Physics out there: Baryon Asymmetry of Universe & by Dark Matter Hierarchy problem Plethora of fundamental parameters … B Experiments at Hadron Colliders are well positioned to: Perform precision measurements of CKM Elements with small model dependence. Search for New Physics via CP phases Search for New Physics via Rare Decays Help 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 Lb b & c quark Production Structure: B(s) spetroscopy, b-baryon states
Bc decays
FPCP 2003 K. Honscheid Ohio State Importance of Particle Identification
BTeV RICH Detector
Liquid
Gas
FPCP 2003 K. Honscheid Ohio State Measuring a Using Bo®rp ® p+p-po
A Dalitz Plot analysis gives both sin(2a) and cos(2a) (Snyder & Quinn)
Measured branching ratios are: Nearly empty - o - -5 B(B ®r p ) = ~10 (r polarization) B(Bo®r-p+ + r+p-) = ~3x10-5 B(Bo®ropo) <0.5x10-5
Snyder & Quinn showed that 1000-2000 tagged events are sufficient
Not easy to measure Slow p0’s p0 reconstruction Dalitz Plot for Bo®rp Not easy to analyze 9 parameter likelihood fit
FPCP 2003 K. Honscheid Ohio State Yields for Bo®rp Based 9.9x106 background events Bo®r+p- 5400 events, S/B = 4.1 Bo®ropo 780 events, S/B = 0.3 Bo®ropo Background Signal
po g g
FPCP 2003 K. Honscheid m (GeV) m (GeV) Ohio State B B Our Estimate of Accuracy on a
Geant simulation of Bo®rp, (for 1.4x107 s)
a (gen) R a (recon) Da res Rnon 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
minimum c2
Example: 1000 Bo®rp signal + backgrounds With input a=77.3o
FPCP 2003 non-resonant resonant K. Honscheid Ohio State non-rp bkgrd non-rp bkgrd Rare b Decays
Search for New Physics in Loop diagrams New fermion like objects in addition to t, c or u New Gauge-like objects in addition to W, Z or g
Inclusive Rare Decays including b®sg l+l- b®dg g, b®sl+l- Exclusive Rare Decays such as B®rg, K*g B®K*l+l- Dalitz plot & polarization
FPCP 2003 K. Honscheid o Ohio State B ®K*g Electromagnetic Calorimeter The 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 3 Block size 2.7 x 2.7 x 22 cm (25 Xo) ~23000 crystals • Photomultiplier readout (no magnetic field) • Pre-amp based on QIE chip (KTeV) • Energy resolution Stochastic term 1.6% Constant term 0.55% • Position resolution Å217mm s x = 3526 mm / E
FPCP 2003 K. Honscheid Ohio State PbWO4 Calorimeter Properties
Property Value Property Value Density(gm/cm2) 8.28 Transverse block size 2.7cm X 2.7 cm Radiation Length(cm) 0.89 Block Length 22 cm Interaction Length(cm) 22.4 Radiation Length 25 Light Decay time(ns) 5(39%) Front end Electronics PMT (3components) 15(60%) Inner dimension +/-9.8cm (X,Y) 100(1%) Energy Resolution: Refractive index 2.30 Stochastic term 1.6% (2.3%) Max of light emission 440nm Constant term 0.55%
Temperature Spatial Resolution: s x = 3526 mm / E Coefficient (%/oC) -2 Å217mm Light output/Na(Tl)(%) 1.3 Outer Radius 140 cm--215 cm Light output(pe/MeV) $ driven into 2” PMT 10 Total Blocks/arm 11,500
FPCP 2003 K. Honscheid Ohio 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 2003 K. Honscheid Ohio State Muon System
Provides Muon ID and Trigger Trigger for interesting physics states Check/debug pixel trigger fine-grained tracking + toroid Stand-alone mom./mass trig. Momentum “confirmation” Basic building block: Proportional tube “Planks” ~3 m
toroid(s) / iron
track from IP 2.4 m half height
FPCP 2003 K. Honscheid Ohio State Polarization in Bo®K*om+m-
BTeV data compared to Burdman et al calculation
Dilepton invariant mass distributions, Ali et. al, hep-ph/9910221 forward-backward asymmetry discriminate among the SM and various supersymmetric theories. (Ali, Lunghi, Greub & Hiller, hep-ph/0112300)
+ - FPCP 2003 One year for K*l l , enough to determine if New Physics is present K. Honscheid Ohio 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 dependence discover 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 DAQ a superb charged particle tracking system good particle identification excellent photon detection
FPCP 2003 K. Honscheid Ohio State Additional Transparencies
FPCP 2003 K. Honscheid Ohio State Physics Reach (CKM) in 107 s
Reaction B(B) # of S/B Parameter Error or (x10-6) Events (Value) - o Bs® Ds K 300 7500 7 g - 2c 8 - Bs® Ds p 3000 59,000 3 xs (75) o - B ®J/y KS J/y ®l+ l 445 168,000 10 sin(2b) 0.017 o o B ®J/y K , Ko ® p l n 7 250 2.3 cos(2b) ~0.5 B-®Do (K+p-) K- 0.17 170 1 B-®Do (K+K-) K- 1.1 1,000 >10 g 13o
Bs®J/y h, 330 2,800 15
Bs®J/y h¢ 670 9,800 30 sin(2c) 0.024 Bo®r+p- 28 5,400 4.1 Bo®ropo 5 780 0.3 a ~4o Reaction B(B) # of S/B Parameter Error (x10-6) Events - - o B ®KS p 12.1 4,600 1 <4 + Bo®K+p- 18.8 62,100 20 g Theory err.
FPCP 2003 Bo®p+p- 4.5 14,600 3 Asymmetry 0.030 K. Honscheid Ohio State Bo®K+ K- 17 18,900 6.6 Asymmetry 0.020 A simplified trigger comparison
FPCP 2003 K. Honscheid Ohio State From U. Egede UnitarityUnitarityTrianglesTriangles
0 + - Bd ® p p 0 0 BS ® DS p Bd ® r p
0 *0 Bd ® DK 0 BS ® DSK 0 0 0 Bd ® J/y KS Bd ® D* p, 3p
dg = c
B 0 ® J/y f FPCP 2003 S K. Honscheid Ohio State From N. Harnew Pixel Test Beam Results
No change after 33 Mrad (10 years, worst case, BTeV)
Analog output of pixel amplifier before and after 33 Mrad irradiation. 0.25m CMOS design verified radiation hard with both g and protons. Track angle (mr)
FPCP 2003 K. Honscheid Ohio State Forward Tracker
Prototype Straw tracker being constructed for FNAL beam test summer/fall 2002
Drawing Predicted performance - Of forward Momentum resolution is better Microstrip than 1% over full momentum and tracker FPCP 2003 angle range K. Honscheid Ohio State HPD Schematic for BTeV RICH
HPD Tube HPD Pixel array HPD Pinout
Pulse Height from 163 pixel prototype HPD. Note pedestal, 1, 2, 3 pe peaks
FPCP 2003 K. Honscheid Ohio State Prop Tube Planks
Basic Building Block: Proportional Tube “Planks”
3/8” diameter Stainless steel tubes (0.01” walls) “picket fence” design 30 m (diameter) gold-plated tungsten wire Manifolds are brass soldered to tubes (RF sheilding important!) Front-end electronics: use Penn ASDQ chips, modified CDF COT card Try “D0 fast gas” 88% Ar - 10% CF4 - CO2 or 50% Ar – 50% Eth.
FPCP 2003 K. Honscheid Ohio State Plank Cosmic Ray Tests
Cosmic Ray Test Stand
FPCP 2003 K. Honscheid Ohio State BTeV Data Acquisition Architecture
BTeV detector
7 Front-end electronics > 2 x 10 channels
PIX m Level-1 7.6 MHz 800 GB/s L1 muon Global Level-1
L1 vertex
Level-1 Buffers Information Transfer GL1 accept L1 rate reduction: ~1/100 Control Hardware Req. data for ITCH crossing #N Crossing #N
Level 2/3 Crossing Switch RDY
#1 Level-2/3 Processor Farm L2/3 rate reduction: ~1/20 #2 #m-1 #m Level-2/3 Buffers
Level-3 accept Data Logging 4 KHz 200 MB/s
FPCP 2003 K. Honscheid Ohio State