Abstract:Recently, a new family of low-cost X-radiation detectors have been developed, based on semiconducting polymer diodes, which are easy to process, mechanically flexible, relatively inexpensive, and able to cover large areas. To test their potential for radiotherapy applications such as beam monitors or dosimeters, as an alternative to the use of solid-state inorganic detectors, we present the direct detection of 6 MV X-rays from a medical linear accelerator using a thick film, semiconducting polymer detector. The diode was subjected to 4 ms pulses of 6 MV X-rays at a rate of 60 Hz, and produces a linear increase in photocurrent with increasing dose rate (from 16.7 to 66.7 mGy.s -1). The sensitivity of the diode was found to range from 13 to 20 nC.mGy -1 .cm -3 , for operating voltages from -50 to -150 V, respectively. The diode response was found to be stable after exposure to doses up to 15 Gy. Testing beyond this dose range was not carried out. Theoretical calculations show that the addition of heavy metallic nanoparticles to polymer films, even at low volume fractions, increases the X-ray sensitivity of the polymer film/nanoparticle composite so that it exceeds that for Published in: Physics in Medicine and Biology, 58 (2013) 2 silicon over a wide range of X-ray energies. The possibility of detecting X-rays with energies relevant to medical oncology applications opens up the potential for these polymer detectors to be used in detection and imaging applications using medical X-ray beams. IntroductionOver the past 60 years, radiation oncology apparatus has been developed, based on Linear Particle a lower activation energy is required to produce an ionisation pair (approx. 10 times lower), and the higher material density leads to a higher efficiency (up to 10 3 times greater), making them ideal produced from a medical LINAC. In this case, the attenuation coefficient of the polymer for the high energy X-rays is approx. 30 times less than that for the lower energy X-rays. Methods MaterialsPoly([9,9-dioctylfluorenyl-2,7-diyl]-co-bithiophene) (F8T2, number-average molecular weight (Mn) = 45,000 g.mol -1 , weight-average molecular weight (Mw) = 120,000 g.mol -1 ) was prepared as previously reported. [Theim et. al. 2005 accelerated at 100 rpm/s to 500 rpm and held for 60 s, 3) accelerated at 100 rpm/s to 2000 rpm and held for 30 s, 4) decelerated at 100 rpm/s. This procedure produced a relatively smooth polymer film with a thickness of approx. 10 μm. After this, the films were typically dry to the touch; a short period of drying under atmospheric conditions was however required for some films, before annealing under vacuum at 110°C for 24 h. The thickness of the polymer layers was subsequently measured using a surface profilometer (Dektak 8, Veeco Instruments). To complete the diode, gold (Au) or Al electrodes (100 nm thick, 0.5 x 0.5 cm 2 ), depending on the substrate used, were thermally evaporated onto the F8T2, through a shadow mask, at a pressure of 10 -6 mbar. The diodes were connected to the measurem...

The High Granularity Timing Detector (HGTD) will be installed in the ATLAS detector to mitigate pile-up effects during the High Luminosity (HL) upgrade of the Large Hadron Collider (LHC) at CERN. The design of the HGTD is based on the use of Low Gain Avalanche Detectors (LGADs), with an active thickness of 50 μm, that allow to measure with high-precision the time of arrival of particles. The HGTD will improve the particle-vertex assignment by measuring the track time with a resolution ranging from approximately 30 ps at the beginning of the HL-LHC operations to 50 ps at the end. Performances of several unirradiated, as well as neutron- and proton-irradiated, LGAD sensors from different vendors have been measured in beam test campaigns during the years 2018 and 2019 at CERN SPS and DESY. This paper presents the results obtained with data recorded by an oscilloscope synchronized with a beam telescope which provides particle position information within a resolution of a few μm. Collected charge, time resolution and hit efficiency are presented. In addition to these properties, the charge uniformity is also studied as a function of the position of the incident particle inside the sensor pad.

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