Final size planar edgeless silicon detectors for the TOTEM experiment

Abstract

The TOTEM experiment will detect leading protons scattered in angles of microradians from the interaction point at the Large Hadron Collider. This will be achieved using detectors with a minimized dead area at the edge. The collaboration has developed an innovative structure at the detector edge reducing the conventional dead width to less than 100 μm, still using standard planar fabrication technology. In this new development, the current of the surface is decoupled from the sensitive volume current within a few tens of micrometers. The basic working principle is explained in this paper. Final size detectors have been produced using this approach. The current-voltage and current-temperature characteristics of the detectors were studied and the detectors were successfully tested in a coasting beam experiment.

Summary of Physics Results from the TOTEM Experiment

“…They host silicon detectors which are moved very close to the beam, when it is in stable conditions. As the detection of protons at such small scattering angles requires a detector active area as close to the beam as ∼ 1 mm, a novel "edgeless planar silicon" detector technology has been developed for TOTEM RPs in order to have an edge dead zone minimized to only ∼ 50 µm [6]. Each RP station is composed of two units, in order to have a lever harm for a better local track reconstruction and a higher efficiency of trigger selection by track angle.…”

Charge collection measurements on slim-edge microstrip detectors

“…Conventional planar silicon detectors are characterized by insensitive border regions, of typically 1 mm width, occupied by guard-ring structures used to gradually reduce the voltage applied to the detector sensitive-area, or by implants reducing the voltage drop across the edge. Slim-edge detectors with a minimized dead border width would be very useful both for Large Hadron Collider (LHC) experiments [1] and in medical applications such as Proton Computer Tomography [2] and digital X-ray imaging [3]. Recently a new technique has been proposed which combines laser scribing and cleaving with the deposition of a conformal coating to properly shape the field at the edges [4,5].…”

The TOTEM Experiment at the CERN Large Hadron Collider

“…The capillary will be coiled up in the pot to minimise the heat loss and the need of additional insulation. Edgeless silicon detectors have been tested in autumn 2004 with a muon beam in the SPS X5 area at CERN [13,17]. The sensors had the final size and strip pitch of 66 µm.…”