1. HallA/SBS – Front Tracker PARAMETERDESIGN VALUE Microstrip Silicon Detector Number of tiles/plane and size2 @@@ Number of planes2 Size of the single plane@@@ Number of microstrips / strip pitch@@@@ GEM Detector GEM modules/plane and size3 – 40x50 cm2 Number of planes6 Size of the single chamber40x150 cm2 Number of x/y strips and pitch41472 - 0.4 mm Expected Performance Coverage of transverse area (3 m from target) 40x120 cm2 Hit spatial resolution< 100 um Sustained event acquisition rate20 kevents/s Detector - TECHNICAL PARAMETERS the corresponding particle momenta (with the help of the bending magnet), origin at target (assuming the beam direction). Together with the Polarimeter Trackers information, the reconstructed tracks will also provide the deflection angles of the protons in the Polarimeter and therefore permit the measurement of the scattered proton polarization. The FT in its full configuration includes 2 small planes of microstrip silicon detectors (uSiD) and 6 planes of Gaseous Electron Multiplier chambers (GEM). @@@ due righe su doves si trovano le uSiD (vicino al bersaglio) @@@ @@@ e come sono fatte @@@ The Front Tracker (FT) is the tracker of the primary charged particles in the SBS spectrometer. Its modular design permits flexible configuration and optimized use in different high luminosity experimental configurations and conditions. The FT shall permit the reconstruction of the trajectories of the primary charged particles (those coming from the target), through the 3D positions of the localized ionization (hits) produced in the active volume of its chambers. The reconstructed trajectories (or tracks) will be used to measure: Silicon Detector Image The GEM chambers sits at about 300 cm from the target; each chamber is made of independent GEM modules assembled as shown in figure and supported by a robust “service” frame. Electronics, cabling, gas pipes, and corresponding patch panels are fixed and supported by the service frame.

2. Contact: E. Cisbani GEM Detector lead (evaristo.cisbani@iss.infn.it) +39 0649902847evaristo.cisbani@iss.infn.it G. M. Urciuoli SiD Detector lead (guido.maria.urciuoli@rm1.infn.it) +39 xguido.maria.urciuoli@rm1.infn.it C. Sutera GEM Detector Assembly (cettina.sutera@ct.infn.it) xcettina.sutera@ M. Jones SBS Project Manager (jones@jlab.org) 757-269-x@jlab.org C. Keppel Hall A leader (keppel@jlab.org ) 757-269-xkeppel@jlab.org Detector Details @@@qualche indicazione in piu’ sui SiD@@@ Each GEM module is made of 3 GEM foils (in single mask technique) separated by 2 mm. A drift foil is at 3 mm from the first GEM foil and a kapton readout foil is placed after the third GEM at 2 mm. The GEM and Drift foils are glued on thin Permaglas (also known as Durastone) frames (8 mm wide), while the readout foil is glued on a honeycomb plane which represents the main mechanical support of the module. Thee GEM foils are taken at the 2 mm distance by 5 tiny Permaglas “spacers” (0.3 mm wide). The readout foil has a double layer of x and y strips, with 0.4 mm pitch for a total of 1024 strips on x and 1280 strips on y. Two thin (12 um) mylar windows close the gas volume of the GEM module; one mylar window is glued before the drift, the other after the honeycomb plane, at 3 mm from it. Readout electronics The about 100 k strips are readout by radiation tolerant front-end cards based on the APV25 chip. The cards are grouped (4 or 5), connected and supported by passive boards (Backplanes or BCK). Up to 16 cards (4 backplanes) can be connected to one VME module (MPD) which manages the front-end cards, provides the ADCs to convert the APV25 multiplexed analog signals into digital information and performs a preliminary process of the converted data, such as pedestal subtraction, common noise removal and zero suppression (sparse readout). Each front end card hosts one APV25 and it is able to read 128 channels. The APV25 has essentially a preamp+shaper stage followed by 192 cells analog pipeline which permit 3.4 us trigger latency (40 MHz clock). Signals are sampled at 40 MHz. The front end cards and backplanes are radiation tolerant. The backplane is a PCB for signal routing, which can connect up to 5 cards. It hosts two radiation tolerant voltage regulators which provide the power to the cards. The backplane + front end cards are powered by a single voltage level of 3.3-3.5 V. The electronics designed by INFN has been adopted for the readout of the GEM in the Olympus experiment and the SBS back-tracker. Construction Strategy and Project Leadership –Project is lead and funded by INFN. –The assembling of the GEM modules takes place in the clean room of INFN-Catania; testing and chamber integration is mainly performed in Rome. Design and preliminary testing of the electronics performed by INFN-Genova. –Bounding and assembling of the SiD is performed in the IFN Clean Room in Rome …. Project Status Main design of the FT completed by end of 2013 Procurement of most of the FT components completed by end of 2014 First FT GEM chamber will be delivered at JLab Spring/2015. Delivery of GEM chamber will continue till end of 2016. First SiD @@@@