Emulsion sheet doublets as interface trackers for the OPERA experiment
ABSTRACT: New methods for efficient and unambiguous interconnection between electronic position
sensitive detectors and target units based on nuclear photographic emulsion films have been
developed. The application to the OPERA experiment, that aims at detecting nm ⇋nt oscillations
in the CNGS neutrino beam, is reported in this paper. In order to reduce background due to latent
tracks collected before installation in the detector, on-site large-scale treatments of the emulsions
(“refreshing”) have been applied. Changeable Sheet (CSd) packages, each made of a doublet of
emulsion films, have been designed, assembled and coupled to the OPERA target units (“ECC
bricks”). A device has been built to print X-ray spots for accurate interconnection both within the
CSd and between the CSd and the related ECC brick. Sample emulsion films have been extensively
scanned with state-of-the-art automated optical microscopes. Efficient track-matching and
powerful background rejection have been achieved in tests with electronically tagged penetrating
muons. Further improvement of in-doublet film alignment was obtained by matching the pattern
of low-energy electron tracks. The commissioning of the overall OPERA alignment procedure is
in progress.
KEYWORDS: Particle tracking detectors; Detector design and construction technologies and
materials; Large detector systems for particle and astroparticle physics; Detector alignment and
calibration methods (lasers, sources, particle-beams). / 570.00 Кб