1. Esperimento DIAMED Consuntivo 2013 INFN gruppo IV Coordinatore: Gianluca Verona Rinati Unità: Roma2, To 1

2. Single crystal diamond based in-vivo dosimeters Optimization of the sensitivity Depletion layer from 1 µm up to 4µm with no bias voltage applied Flat housing Linearity index of about 0.999 Leakage current below 80 fA up to 40°C 2

3. Single crystal diamond based multi-pixel dosimeter Fabrication of a 3×3 diamond matrix New version of the dedicated readout chip Embedded in epoxy resin Developed new control software Tested under linac beams at PTV 3

4. Single crystal diamond based multi-pixel dosimeter Linearity plot (the central pixel) Dose rate dependence (central pixel) Dose-map acquired by the pixel detector for three different configuration of the multileaf collimator 4

5. 5 “smart-cut” technique The smart-cut process (animazione) HPHT substrate B-doped CVD graphite intrinsic CVD New equipment for etching at high temperature in ozone (fondi INFN-DiaMed) → direct fabrication free-standing high-quality µm-thin diamond layers → automatized PC-driven control → fully operational

6. Tests on surface-exposed graphite → fast and effective removal of graphite from the surface on mm-sized areas Tests on sub-superficial grpihite → sub-optimal results → the etching process is still diffusion limited → etching from 10 2 µm sized areas → fabrication of relatively small free-standing layers before etchingafter etching 8 µm thickness free-standing high-quality 6

7. 7 Buried graphite electrodes devices Fabrication of sub-superficial graphitic microelectrodes Test detector homoepitaxial single-crystal CVD diamond grown @ UniRoma “Tor Vergata” 50 μm thick intrinsic layer on HPHT substrate [N], [B] < 5×10 14 cm -2 ion μ-beam line @ Legnaro National Laboratories ions: 2 MeV He+ (range  3 μm) ion fluence: 1.5×1017 cm-2 annealing: 2 hrs @ 1100 °C in vacuum

8. IBIC characterization ion μ-beam line @ Ruđer Bošković Institute ions: 4 MeV He + (range  8 μm)   4 μm frontal geometry Formation of anomalous polarity pulses positive pulsesnegative pulses Numerical modeling and experimental results → good agreement between data and the FEM model based on the Shockley-Ramo- Gunn theorem 8

9. Fabrication process of the novel 3D detector: a) An intrinsic diamond layer, 50 µm in thickness, is directly grown by Microwave Plasma CVD on HPHT diamond substrate. b) One micron of nickel mask deposited on CVD diamond surface by sputtering system and patterned by photolithography technique. c) Etching of diamond by RIE (6 µm depth). d) The Ni mask was removed by chemical etching from the diamond surface. e,f) Metallic interdigitated electrodes fabrication 6 µm A 3D electrode geometry for the enhancement of charge collection in diamond detectors. Comparison between standard surface electrodes and 3D electrodes Both devices are constituted by metal fingers 10 µm in width with 10 µm spacing 9

10. Simulations based on the Shockley- Ramo-Gunn Theory by solving numerically the Laplace’s equation Finite element method solver: Comsol Multiphysics 4.3 b Good consistency with FEM simulations Simulation parameters: hole lifetime: 400 ps, hole mobility: 2000 cm 2 /V/s, electron lifetime:15 ps, electron mobility: 1700 cm 2 /Vs Finite Element Method (FEM) simulations of such device highlight the enhancement of the CCE in the inter-electrode region of the device with respect to that obtained by standard superficial electrodes Finite Element Method (FEM) simulations 3D detector The contour plots indicate the electric potential and the weighting potential distribution when a bias voltage of -20 V is applied between the electrodes. The relevant electric field lines are superimposed. Planar detector 10

11. Ion beam induced charge (IBIC) measurement - 20 V - 50 V - 20 V - 50 V Planar 3D 25 µm IBIC characterization were carried out at the micro-beam facility of the Italian National Laboratories of Legnaro by raster-scanning a rarefied 1 MeV proton micro-beam over the active area of the diamond detectors. Beam spot size: ~ 5 μm Current: ~ 100 ions/s Energy: 1 MeV Ions: H+ Penetration depth in diamond: 8.13 µm Scanned area: 170×25 μm 2 V Bias OUT Experimental and simulated CCE profile 11

12. Mandapaka, A.K., Ghebremedhin, A., Patyal, B., Marinelli, M., Prestopino, G., Verona, C., Verona-Rinati, G. Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams (2013) Medical Physics, 40 (12), art. no. 121702 Bagalà, P., Di Venanzio, C., Falco, M.D., Guerra, A.S., Marinelli, M., Milani, E., Pimpinella, M., Pompili, F., Prestopino, G., Santoni, R., Tonnetti, A., Verona, C., Verona-Rinati, G. Radiotherapy electron beams collimated by small tubular applicators: Characterization by silicon and diamond diodes (2013) Physics in Medicine and Biology, 58 (22), pp. 8121-8133 Forneris, J., Grilj, V., Jakšić, M., Olivero, P., Picollo, F., Skukan, N., Verona, C., Verona-Rinati, G., Vittone, E. Measurement and modelling of anomalous polarity pulses in a multi-electrode diamond detector (2013) EPL, 104 (2), art. no. 28005 Zani, M., Bucciolini, M., Casati, M., Talamonti, C., Marinelli, M., Prestopino, G., Tonnetti, A., Verona-Rinati, G. A synthetic diamond diode in volumetric modulated arc therapy dosimetry (2013) Medical Physics, 40 (9), art. no. 092103 Marinelli, M., Milani, E., Prestopino, G., Verona, C., Verona-Rinati, G., Cutroneo, M., Torrisi, L., Margarone, D., Velyhan, A., Krasa, J., Krousky, E. Analysis of laser-generated plasma ionizing radiation by synthetic single crystal diamond detectors (2013) Applied Surface Science, 272, pp. 104-108 Forneris, J., Grilj, V., Jakšić, M., Lo Giudice, A., Olivero, P., Picollo, F., Skukan, N., Verona, C., Verona-Rinati, G., Vittone, E. IBIC characterization of an ion-beam-micromachined multi-electrode diamond detector (2013) Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, 306, pp. 181-185 Di Venanzio, C., Marinelli, M., Milani, E., Prestopino, G., Verona, C., Verona-Rinati, G., Falco, M.D., Bagalà, P., Santoni, R., Pimpinella, M. Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry (2013) Medical Physics, 40 (2), art. no. 021712 Fabbri, A., Falco, M.D., De Notaristefani, F., Galasso, M., Marinelli, M., Orsolini Cencelli, V., Tortora, L., Verona, C., Verona Rinati, G. Dedicated multichannel readout ASIC coupled with single crystal diamond for dosimeter application (2013) Journal of Instrumentation, 8 (2), art. no. C02042 A. Fairchild, A. D. Greentree, D. W. M. Lau, P. Olivero, F. Picollo, S. Rubanov, S. Prawer "Direct measurement and modelling of internal strains in ion-implanted diamond", F. Bosia, N. Argiolas, M. Bazzan, B., Journal of Physics: Condensed Matter 25, 385403 (2013) Publications 2013 12