Status report on MURAY telescope R&D

1. Status report on MURAY telescope R&D Pasquale Noli on behalf of Mu-Ray collaboration

2. Outline • Motivation • Measurement principles • The MURAY telescope • Fiber optical connector • SiPM hybrid connector • SiPM from IRST-FBK test • Front End electronic and DAQ • Conclusions SIF 2010 Bologna

3. Conduit length = 8000m Gas content = 5 wt% Seismic, gravimetric, electromag. methods: Several km 100,000 ton/s Pompei eruption 1631 eruption 20 50 200 300 100 Motivation Muon radiography: few hundreds m Volcano-eruption dynamics mostly depend on • the gas content • the chemical composition of the magma • the lava-conduit dimensions and shape. • Traditional measurement methods : • gravimetric • seismological • electromagnetic • Have spatial resolutions of the order of several hundredmeters. • Muonradiographycan improve resolutions • by one order of magnitude. Simulated Mass eruption rate vs. Conduit SIF 2010 Bologna

4. Muon Radiography • Muon radiography is based on the measurement of the absorption of cosmic muons inside matter. “The first application was realized in 1971 by Alvarez and collaborators for the search of unknown burial cavities in the Chephren pyramid.” • In recent years Tanaka and collaborators, from University of Tokyo, have demonstrated the possibility to use this technique, to study the internal structure of volcanoes. • The spatial resolution that can be obtained with this method is of the order of 10 m. SIF 2010 Bologna

5. Measurement principles (I)(No background hypothesis) • The observed number of muons is a function of the muon flux crossing the volcano volume seen along the direction (,) the absorption factor A, and the detector efficiency  : • In the limit of neglecting the  dependence of cosmic ray flux, the product of the muonflux times detector efficiency can be measured using special runs pointing to “free” sky region • Then the absorption can be evaluated as: SIF 2010 Bologna

6. Measurement principles (II) • Starting from the theoretical muon flux distribution f (Thompson and Whalley expression) , we compute the expected muon transmission rate through water meter equivalent for each  direction. • For each (θ,) direction we can obtain the mean rock density from the ratio between: • the water meter equivalent length relative to A. • thickness of montain. . SIF 2010 Bologna

7. The MURAY telescope (I) Two 2x2 m2 X-Y stations • Triangular shape scintillators (from Fermilab) • Scint. light collected by WLS one-side mirrored fiber • (BCF92 fast response fibers from Bicron) • Dedicated 32 fibers optical connector • Dedicated SiPM from FBK-IRST . • They have 1.4 mm diameter and 70x70 mm2 • cell size, with 292 cells in total • Dedicated hybrid hosting 32 SiPMs • SiPM temperature control by Peltier Cells • SPIROC 0 ASIC FEE (from Orsay group) • Dedicated read-out and acquisition board • Expected performances: • ≈3 mm space resolution (by measurement of • charge sharing between two adjacent strips) • ≈ 1ns time resolution • O(10) W power consumption SIF 2010 Bologna

8. The MURAY telescope (II) 32 scintillator bars module (0.5 m large), with bars glued together and on a G11 fiberglass support plate 0.5 m Fibers’ connector 2 m SiPM hybrid connector SIF 2010 Bologna

9. The MURAY telescope prototype (I) • A prototype is under construction • 3 X-Y stations 1x1 m2 area • SPIROC 1 ASIC FEE A special tool designed and built for precision assembly of the 32 bars in a plane SIF 2010 Bologna

10. Fiber optical connector A special connector (made of black Plexiglas) has been developed for high-precision positioning of the fibers in front of the SiPMs. 32 fibers are glued on the connector that will be fixed to the module chassis. The fiber connector is mechanically coupled with a hybrid circuit hosting the SiPMs. SIPM SIDE Al PROTOTIPE FIBER SIDE Al prototype O RING SEAT MAGNIFICATION OF THE GLUE TANKS Reference hole SIF 2010 Bologna

11. SiPM hybrid connector In order to optimize the cooling by Peltier cells, we decided to group together 32 die SiPM in a single PCB. One side of the Peltier cells is thermally in contact with the back side of the PCB. A rubber O-ring ensures light and air tightness. Two temperature sensors are located on the PCB for the Peltier cells control circuit. The first 5 hybrid PCB have been produced in Florence. SIF 2010 Bologna

12. First test on SiPM We studied the V break-down of the SiPM of first hybrid connector. SIF 2010 Bologna

13. Front End electronic and DAQ (I) Spiroc 1: we have 18 chips, enough for the 1x1 m2 prototype The FE board (Slave) and the trigger-DAQ board (Master) have been designed. The first prototypes have been realized and are under test. SLAVE MASTER SIF 2010 Bologna

14. Conclusions • We are presently assembling the first MU-RAY prototype module • The SiPMs produced at IRST-FBK are assembled on hybrid connector and are under test in Naples. • A special optical connector with SiPMs and Peltiercooling has been designed and built. • The readout electronics has been designed and is under test. SIF 2010 Bologna