SMT H-disks SMT F-disks SMT barrels

Cutoff

tracking 3 pT>180 MeV

calorimetry 5 E>few GeV

ID 2 pT>1.5 GeV

Pseudorapidity: Pseudorapidity: =-ln[tan/2)]

432.442.03210.8802.15.7101515.440.44590(o)

B Physics Program Depends Strongly On:

Muon System Tracking System

How Do B Physics Events Look In The DØ Detector?

Diagram of oscillated Bs event Same event in detector

Bs

μ+

νμ K-

K+Bd

μ+

νμ

π-

K-

K+BsBd

+

Ds-

• We trigger on ’s from semi-leptonic B decays.

• By conservation of flavor, every event that has one b(b) quark must have at least one b(b).

• Can trigger on hadronic B decays by using from B decaying on the other side of the event.

• Mean decay length of all produced B mesons ~ few mm.

• Almost all B mesons decay into at least one charmed hadron, e.g. D0, D*, Ds, which also have long decay length.

•So, a typical bb event has 5 vertices

• 1 primary, 2 secondary from B decays, 2 tertiary from charmed decays

• Resolution of tracking system is crucial to reconstructing these vertices.