The ATLAS MDT remote calibration centers

The precision chambers of the ATLAS Muon Spectrometer are built with Monitored Drift Tubes (MDT). The requirement of high accuracy and low systematic error, to achieve a transverse momentum resolution of 10% at 1 TeV, can only be accomplished if the calibrations are known with an accuracy of 20 μm. The relation between the drift path and the measured time (the socalled r-t relation) depends on many parameters (temperature T, hit rate, gas composition, thresholds,...) subject to time variations. The r-t relation has to be measured from the data without the use of an external detector, using the autocalibration technique. This method relies on an iterative procedure applied to the same data sample, starting from a preliminary set of constants. The required precision can be achieved using a large (few thousand) number of non-parallel tracks crossing a region, called calibration region, i.e. the region of the MDT chamber sharing the same r-t relation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85421/1/jpconf10_219_022028.pd

Preliminary investigation into the recovery of explosives from hair

Sampling of hair has proved to be a useful non-invasive method for detecting illicit drugs. This study examined the viability of hair as a surface from which explosive traces can be recovered and showed that as little as one-hour vapour exposure can result in measurable traces of explosives. Contamination of the hair may result from direct contact with explosive particles or from secondary contact by hand. Also the paper demonstrates that hair can concentrate explosive from the ambient vapour of a variety of military explosives. It was found that the amount of TNT picked up by the hair increased with time of vapour exposure. The data also suggested that unwashed hair may pick up more TNT than washed hair. © The Forensic Science Society 2002