Diamond has a potential for Intensity Modulated Radiotherapy (IMRT) applications, being a solid-state nearly tissue equivalent material, with the possibility to be grown in large diameter wafers by ...Chemical Vapour Deposition (CVD). We present a monolithic polycrystalline CVD diamond dosimeter and first results in an IMRT beam. Our device shows to be able to cope with the complex temporal/spatial structure of the IMRT field.
High Energy Physics experiments at future very high luminosity colliders will require ultra radiation-hard silicon detectors that can withstand fast hadron fluences up to 10/sup 16/ cm/sup -2/. In ...order to test the detectors radiation hardness in this fluence range, long irradiation times are required at the currently available proton irradiation facilities. Energetic (58 MeV) Lithium (Li) ions, with experimental hardness factor about two orders of magnitude higher than 24 GeV protons for 280-300 /spl mu/m thick detectors, could represent a promising alternative radiation source. In this study, the degradation mechanisms in single pad p/sup +/-n Standard Float Zone (STFZ) and Diffusion Oxygenated Float Zone (DOFZ) Si detectors irradiated with Li ions up to the fluence of 2.9/spl times/10/sup 12/ Li/cm/sup 2/ have been investigated by means of Photo Induced Current Transient Spectroscopy and Thermally Stimulated Currents. Results are compared with the radiation damage induced by 24 GeV proton, 1 MeV neutron and /sup 60/Co /spl gamma/-ray irradiation. The critical Li ion fluence for cluster formation is found to be in the range 4.1-21/spl times/10/sup 11/ Li/cm/sup 2/ and its correlation to the corresponding value for hadrons is discussed.
We report on the design, manufacturing and first characterisation of pad diodes, test structures and microstrip detectors processed with high resistivity magnetic Czochralski (MCz) p- and n-type Si. ...The pre-irradiation study on newly processed microstrip detectors and test structures show a good overall quality of the processed wafers. After irradiation with 24
GeV/
c protons up to 4×10
14
cm
-2 the characterisation of n-on-p and p-on-n MCz Si sensors with the
C–
V method show a decrease of the full depletion voltage and no space charge sign inversion. Microscopic characterisation has been performed to study the role of thermal donors in Czochralski Si. No evidence of thermal donor activation was observed in n-type MCz Si detectors if contact sintering was performed at a temperature lower than 380
°C and the final passivation oxide was omitted.
Humidity sensors based on cluster assembled nanostructured carbon films in capacitive configuration have been fabricated and characterized. An electronic read-out system has been designed and ...implemented in order to measure the complex impedance of the device under operation. The sensor and read-out electronics provide a fully integrated and cost-effective system. Devices under test show a fast dynamic response and a good sensitivity compared to capacitive commercial systems. A linear response is observed for relative humidity in the range up to 70%. Hysteresis is practically absent in this range, while for higher values it is at most in the order of 2%.
Phase Change Materials are proposed for refrigerating systems in discontinuous industrial vacuum processes where temperatures as low as −140 ÷ −100°C are necessary within time-frames representing ...10÷20% of total operating time. An application is proposed for cooling systems used in a Physical Vapour Deposition (PVD) apparatus. A prototype has been manufactured which couples a cryopump with a reservoir filled with MethylCycloPentane (MCP-C6H12) and a distribution line where nitrogen in the gaseous state is flowing. Preliminary tests show that temperatures of about −120°C are actually achieved within time windows compatible with PVD applications.
We have investigated the feasibility of humidity sensors based on nanostructured carbon (ns-C) films produced by supersonic cluster beam deposition (SCBD). The ns-C films have been obtained using ...pure He as the buffer gas in the pulsed microplasma cluster source (PMCS). Films of different thickness (1–10
μm) were deposited on Au contacts: resistive- and capacitive-type devices were manufactured. Resistive sensor show a flat response for relative humidity (%RH) up to 60%. Preliminary measurements performed on capacitive-type devices at room temperature in the relative humidity range 10–70% showed a linear dependence of the capacitance on RH%. Fast rise times and a sensitivity of the order of 0.1–0.5
pF/%RH favourably compare with standard commercial sensors and other advanced capacitive devices made with polymers.
We have measured the radiation tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after ...irradiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm−2 and protons cm−2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irradiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irradiation energy and the irradiation fluence. We find for each irradiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradiated with 24 GeV protons to be and the damage constant for diamond irradiated with 800 MeV protons to be . Moreover, we observe the pulse height decreases with fluence for poly-crystalline CVD material and within statistical errors does not change with fluence for single-crystalline CVD material for both 24 GeV proton irradiation and 800 MeV proton irradiation. Finally, we have measured the uniformity of each sample as a function of fluence and observed that for poly-crystalline CVD diamond the samples become more uniform with fluence while for single-crystalline CVD diamond the uniformity does not change with fluence.
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