100  m Nuclear emulsions are made of micro- crystals of silver halides (AgBr) dispersed in a gelatin layer. The energy released by ionizing particles to the crystals, produces a latent image which is almost stable in time. A chemical development process reduces the irradiated grains to metallic Ag. After fixing and washing to remove undeveloped crystals the gelatin is transparent; the paths of an ionizing particle is visible as sequence of black silver grains about 0.5 m size. Provide:  Three-dimensional spatial information.  Excellent Resolution < 1 m.  High hit density ~ 300 hits/mm. Ideal to detect short-lived particles ( decay) OPERA target: ~ ECC Bricks 8 m Real time analysis: ~ 30 neutrino selected interactions per day; ~ 6000 cm² per day have to be analyzed with a sub- micrometric precision during 5 years data taking. Emulsion sheet (10 x 12 cm 2 ): 2 emulsion layers (44 m ) on both sides of a plastic base (205 m) Move Focal Plane Camera gs camera optical tube objective emulsion transparent slide with vacuum system motorized stage motorized axis condenser lamp auxiliary monitor for real-time display Computer with: frame grabber and vision processor motors and lamp controllers 1. Nuclear Emulsion References:N. Armenise et al., Nucl. Instrum. Meth. A551 (2005) 261; L. Arrabito et al., ArXiv:physics/ , Nucl. Instrum. Meth. A (in press). Presented at the 10th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD06) 1-5 October 2006 Siena, Italy G.Sirri (INFN – Bologna) on behalf of the OPERA Collaboration  beam  beam 2. OPERA experiment Fast automated scanning of emulsion films for the OPERA (CNGS1) experiment 3. OPERA Lead-Emulsion Target 4. Automatic Emulsion Scanning System 5. Emulsion Readout New automatic fast automatic scanning systems have been developed: the European Scanning System (ESS) and the S-UTS in Japan. emulsion plastic base tracks 44 µm 205 µm base tracks cluster microtracks 44 µm Top emulsion layer Bottom emulsion layer 3m3m By adjusting the focal plane of the objective, the whole 44 μm emulsion thickness is spanned and a sequence of 15 tomographic images of each field of view, taken at equally spaced depth levels ( m), is obtained. Emulsion images are digitized, converted into a grey scale of 256 levels, sent to a vision processor board, hosted in the control workstation, and analyzed to recognize sequences of aligned grains (clusters of dark pixels of given shape and size). OPERA is a long baseline experiment (located in the INFN Gran Sasso Underground Laboratories) which will investigate for  → τ oscillations in the parameter range suggested by atmospheric neutrino experiments. The goal is to observe the appearance of τ leptons in a pure  beam produced at the CERN-SPS (the CNGS neutrino beam). The leptons are identified through the direct detection of their decays that, at the CNGS energies, are at distances of 1 mm from the production point. Therefore, a high precision detector is needed. Lead 1 mm ECC Brick (10x13x8 cm³) sequence of 56 Lead and Emulsion sheets The OPERA detector is a hybrid system consisting of electronic detectors and a massive lead-emulsion target segmented into ECC bricks The Emulsion Cloud Chamber (ECC), a sequence of dense material (Lead) sheets, acting as target, interleaved with emulsion sheets, acting as high precision trackers, satisfies the need of both a large mass and a high precision tracking capability. Industrially mass production of films by Fuji Co in 2 years. OPERA detector at Gran Sasso 20 cm²/h [44  m emulsion layer] European Scanning System. Several test exposures at pions beams were performed for estimating the scanning performances. The scanning systems are successfully running with high efficiency (>90%), good signal/background ratio (~2 tracks/cm² /[angle<0.4rad]) and the design speed of 20 cm²/h. The ESS is based on the use of commercial hardware components or developed in collaboration with specialized companies. The ESS reaches the speed of 20 cm²/h in an emulsion volume of 44 μm thickness. This represents an improvement of more than an order of magnitude with respect to the systems developed in the past. The S-UTS uses a dedicated hardware suitable for point scanning with a speed of 1.2 s/prediction (~ 15 min/brick). 1.3 Mpixel ~350 fps Field of View ~ 390x310 m² 6. Scanning performances Position and angular track resolutions as function of the reconstructed angle.  ~1 mm  kink > 20 mrad ~ Emulsion scanning system layout. The three-dimensional structure of a track in an emulsion layer is reconstructed by combining clusters belonging to images at different levels and searching for geometrical alignments. A linear fit to these clusters allows the determination of the track position and angle. After emulsion sheets alignment, tracks are reconstructed in the entire brick. Plastic base ! Emulsion Sheet Reconstruction of a neutrino interaction in a ECC Brick  position = 1  m  angle = 2 mrad The position and angular resolutions at small incident angles are  position = 1 m and  angle = 2 mrad. By adjusting the focal plane of the objective, the whole 44 μm emulsion thickness is spanned at equally spaced depth levels ( m), and a sequence of 15 tomographic images of each field of view is obtained. Emulsion images are digitized, converted into a grey scale of 256 levels, sent to a vision processor board, hosted in the control workstation, and analyzed to recognize sequences of aligned grains (clusters of dark pixels of given shape and size).