Very recently we have shown that organic semiconducting single crystals (OSSCs) can be used as effective direct X-ray detectors [1]. In particular, devices based on solution-grown OSSCs, 4-hydroxycyanobenzene (4HCB) (Figure 1a), have been fabricated and operated in air, under ambient light and at room temperature, at voltages as low as few V, delivering well reproducible performances and a stable linear response to the X-ray dose rate, with notable radiation hardness and resistance to aging. In these experiments a molybdenum tube at 35keV was used as x-rays source; molybdenum has an x-ray spectrum with first a dominant peak at 17.9 keV, a secondary peak at 19.5 keV and a not negligible energy broad tail up to 35keV, due to bremsstrahlung radiation. The modulation of the filament current allows to reach 25mGy/s as minimum dose rate, but this value is too high for most kinds of dosimetric and medical applications. During this beamtime we carried out a series of experiments taking advantage of the SYRMEP setup characteristics, in particular i) of the possibility of achieving a monochromatic photon energy source, typical of synchrotron radiation, ii)of the beam focused on a an area of few mm2, and iii) of the aluminum filters allowing to modulate dose rates on samples with real time irradiation dose measurement through a ionization chamber. In this way we have been able to investigated the x-ray detection properties of 4HCB single crystals with a monochromatic beam, ranging from 10keV to 20keV, and reducing the dose rate down to 0.6 mGy/s, in order to perform a more complete description and analysis of crystal properties.
Esperimento 200954408 presso Sincrotrone ELETTRA Trieste, beamline SISSI sul tema “Study of real-time, anisotropic polaronic transport in semiconducting organic single crystals
FRABONI, BEATRICE
2012
Abstract
Very recently we have shown that organic semiconducting single crystals (OSSCs) can be used as effective direct X-ray detectors [1]. In particular, devices based on solution-grown OSSCs, 4-hydroxycyanobenzene (4HCB) (Figure 1a), have been fabricated and operated in air, under ambient light and at room temperature, at voltages as low as few V, delivering well reproducible performances and a stable linear response to the X-ray dose rate, with notable radiation hardness and resistance to aging. In these experiments a molybdenum tube at 35keV was used as x-rays source; molybdenum has an x-ray spectrum with first a dominant peak at 17.9 keV, a secondary peak at 19.5 keV and a not negligible energy broad tail up to 35keV, due to bremsstrahlung radiation. The modulation of the filament current allows to reach 25mGy/s as minimum dose rate, but this value is too high for most kinds of dosimetric and medical applications. During this beamtime we carried out a series of experiments taking advantage of the SYRMEP setup characteristics, in particular i) of the possibility of achieving a monochromatic photon energy source, typical of synchrotron radiation, ii)of the beam focused on a an area of few mm2, and iii) of the aluminum filters allowing to modulate dose rates on samples with real time irradiation dose measurement through a ionization chamber. In this way we have been able to investigated the x-ray detection properties of 4HCB single crystals with a monochromatic beam, ranging from 10keV to 20keV, and reducing the dose rate down to 0.6 mGy/s, in order to perform a more complete description and analysis of crystal properties.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
