This topic covers the issues related to understanding the luminosity
delivered at the interaction point. In addition to the instantaneous
and total integrated luminosity, many physics analyses also require
a detailed understanding of the differential luminosity spectrum
(dL/dE) resulting mainly from the large beam-beam interactions
in the collision process. All foreseen measurements of particle
masses, for example, are highly sensitive to the exact shape of
this luminosity spectrum. Methods for optimizing the delivered
luminosity will also be considered in this topic, due to the significant
overlap in required instrumentation.
The following is a list of topics and questions which is almost
certainly incomplete. Please feel free to suggest additional questions,
provide answers, or express an interest in thinking about any
of these issues.
- Which analyses require an absolute luminosity measurement,
and with what precision?
- What is the ultimate precision required on the luminosity
- What are the relative luminosity requirements for threshold
scans at high energy?
- What relative luminosity precision is required to calibrate
the energy scale at the Z-pole?
Potential Beam Instrumentation
- Beamstralung monitor
- Pairs monitor
- Laser Wire
- 'Wire' scanner at point of high dispersion
- Radiative bhabha monitor
- Deflection scans
- Bunch length monitor
Potential Detector Measurements
- Bhabha acolinearity
- Low-angle bhabha scattering
- What is the possible variance on short time scales?
- How precise do we need real-time measurements?
- What are the likely correlations with other parameters (energy,
- How often are invasive measurements required?
- How easy is it to trade luminosity for energy spread?
- Just what is the strategy for optimizing delivered lumi?
- Where does the luminosity spectrum monitor go?
- What sort of alignment tolerance is needed for the acolinearity
- How much time is needed to reach the target precision?
- How does an IP boost effect this measurement?
- What kind of instrumentation is really needed to understand
the collision process?
- How well can dL/dE be predicted?
- How can the bunch length be measured, and how important is
- Can a pairs monitor be made to work?
- What is currently envisioned for IP instrumentation, and
where does this fit?