We are forming a new luminsity measurement task force, which will be led by Vincent Hedberg. The charge to this task force is listed below. We thank Vincent for agreeing to take on this essential task. If you are interesting in volunteering to work on these topics, please contact Vincent by email or in person. Benedetto, Marjorie and Witold Charge for the Luminosity Measurement Task Force ================================================= Scope: online & offline determination of absolute luminosity, based on luminosity-capable ATLAS subdetectors, hereafter called "luminosity subdetectors". These currently include: BCM, MBTS, LUCID, ZDC and FCAL. 1. Identify, document & characterize the performance of the various online luminosity algorithms that can be used by each of the luminosity subdetectors. Encourage common approaches, algorithms & procedures wherever practical. 2. For each luminosity subdetector and each of its online algorithms, provide an initial absolute calibration, based on Monte Carlo. This calibration, which should be available before first collisions, will allow a prompt estimate of initial LHC performance, order-of-magnitude consistency checks between the various luminosity subdetectors in ATLAS, as well as provide the infrastructure essential to the longer-term understanding of systematic errors and possible measurement uncertainties. While such a Monte Carlo calibration is obviously subject to substantial physics uncertainties, relative-calibration errors can be minimized by ensuring the mutual consistency of physics generators, detector geometries, software versions etc across the various subdetectors. 3. For each luminosity subdetector and each of its online algorithms, identify & quantify the possible systematics (non-linearities, single-beam background, scan range) that may affect the absolute luminosity calibration by transverse beam-separation scans. 4. Identify and document the improvements that can be brought offline, wrt to the online luminosity determination, e.g. by using more sophisticated algorithms, restricting the luminosity measurement to the physics bunch group(s), etc. 5. Propose offline archiving & accounting strategies for luminosity-subdetector data, that ensures that the recorded (i.e. dead-time corrected) luminosity can be determined offline from scratch and that all the information potentially necessary to systematic studies will be adequately stored.