Lanthanum halide scintillators: Properties and applications Iltis, Alain; Mayhugh, M.R.; Menge, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2006, Letnik:
563, Številka:
2
Journal Article
Recenzirano
BrilLanCe
®-350 and BrilLanCe
®-380, Saint-Gobain Crystals’ trade-names for LaCl
3:Ce and LaBr
3:Ce are being brought to market under exclusive license to Delft and Bern Universities. We are ...reporting the properties of crystals produced with commercially viable processes and find they match others’ observations. These scintillators are bright (60,000 photons/MeV for LaBr
3:Ce) and have very linear response, a combination that leads to very good energy resolution (<3% at 662
keV and about 6% at 122
keV for LaBr
3:Ce). The materials also have fast scintillation decay times (<30
ns) which supports counting applications at very high rate. These fast light output properties also lead to very fast timing (<300
ps coincidence resolving time on 30
mm long pieces of LaBr
3:Ce). These excellent properties are retained at high temperature with only moderate light loss (<10%) at 175
°C in both materials. The detectors carry natural background in La
138 and Ac
227, the latter having been substantially reduced in recent processing. BrilLanCe
®-350 is now available in detectors up to 51
mm diameter while 38
mm diameter is available for BrilLanCe
®-380. Larger sizes are expected.
The light response of cesium iodide crystals was measured at temperatures of 303 K (30 °C) to 203 K (−70 °C) and for gamma sources with energies from 17 keV to 835 keV. Two different methods were ...used to determine the properties of the CsI:Tl crystals. The first used classic analogue spectrometry equipment to check the dependence of energy resolution, intrinsic resolution, and non-proportionality parameters as a variations in temperature, excitation energy, and integration time. The second method registered the light pulses from the PMT without integrating or shaping circuits. At the current stage of the research, the authors have decided to maintain the thesis about the existence of three decay components in CsI:Tl crystals that was employed in previous studies - the light pulse decays were analyzed under this assumption. We observed that the light pulses slowed with a decrease in temperature. When the crystals were cooled from 303 K to 203 K, the fitted decay times increased significantly by factors of two to four. The non-proportionality of the three fitted components was also determined and it was found that the first and second (fast and slow components) exhibited positive non-proportionality while the third (tail component) presented a negative trend for non-proportionality at temperatures of 303 K–203 K. It was found that using sufficiently long integration times, to include compensating trends of all decay components, the light response of CsI:Tl could be proportional.
A custom design cryostat was constructed to study the temperature dependence of relative light yield and non-proportionality trends of scintillators between −182 °C and ＋152 °C. CsI:Tl crystal ...response to γ-rays and X-rays was investigated between 14 keV and 662 keV. Scintillation light was detected by a SiPM device, which was installed on a copper frame separated from the crystal and the cooling rod to enable operating the device at room temperature. The scintillation efficiency of CsI:Tl is peaked at about room temperature. The light yield of CsI:Tl at temperature close to liquid nitrogen boiling point is reduced by a factor of 15 in comparison to room temperature conditions. The non-proportionality of CsI:Tl scintillation response is high at low temperatures and is getting more proportional with increasing temperature.
We present the receiver in the first single-chip GSM/GPRS transceiver that incorporates full integration of quad-band receiver, transmitter, memory, power management, dedicated ARM processor and RF ...built-in self test in a 90-nm digital CMOS process. The architecture uses Nyquist rate direct RF sampling in the receiver and an all-digital phase-locked loop (PLL) for generating the local oscillator (LO). The receive chain uses discrete-time analog signal processing to down-convert, down-sample, filter and analog-to-digital convert the received signal. A feedback loop is provided at the mixer output and can be used to cancel DC-offsets as well to study linearization of the receive chain. The receiver meets a sensitivity of -110 dBm at 60mA in a 1.4-V digital CMOS process in the presence of more than one million digital gates
A custom designed cryostat was constructed to measure the response of a CsI:T1 scintillator in temperature range from -183 degrees C up to +90 degrees C. The light readout was realized using a SiPM ...developed by FBK in near ultraviolet high density (NUV-HD) technology. The crystal and the SiPM were installed on separated copper frames. The crystal was cooled down by liquid nitrogen, while the SiPM was kept at temperature close to room temperature. A separation of 1 mm was kept between the crystal and the photodetector to ensure thermal isolation. The temperature of the crystal could be varied by heaters on the scintillator frame and was continuously monitored using a coil shaped resistance thermometer. The CsI:T1 scintillation decay profiles were recorded in the entire temperature range provided by the cryostat.
Having a parent with Alzheimer's disease (AD) and related dementias confers a risk for developing these types of neurocognitive disorders in old age, but the mechanisms underlying this risk are ...understudied. Although the hippocampus is often one of the earliest brain regions to undergo change in the AD process, we do not know how early in the lifespan such changes might occur or whether they differ early in the lifespan as a function of family history of AD. Using a rare sample, young adults with a parent with late-onset dementia, we investigated whether brain abnormalities could already be detected compared with a matched sample. Moreover, we employed simple yet novel techniques to characterize resting brain activity (mean and standard deviation) and brain volume in the hippocampus. Young adults with a parent with dementia showed greater resting mean activity and smaller volumes in the left hippocampus compared to young adults without a parent with dementia. Having a parent with AD or a related dementia was associated with early aberrations in brain function and structure. This early hippocampal dysfunction may be due to aberrant neural firing, which may increase the risk for a diagnosis of dementia in old age.
Chronic ulcers continue to pose a significant clinical and economic burden for both patients and wound care practitioners. Despite good standard of care (SOC), many wounds fail to heal. Wound healing ...requires a complex cascade of physiologic and immunologic processes as well as proper nutrition. An adequate balance of macro- and micronutrients is important to support the cellular activities that are necessary for repairing and remodeling of tissue. Despite being well documented in a number of clinical studies there continues to be a gap in recognizing nutritional deficits as well as appropriate clinical interventions in patients with chronic wounds. Effective management of malnutrition in patients with chronic wounds requires collaboration among multiple clinical disciplines. A holistic nutritional management approach may yield both clinical and economic benefits.
The introduction of lipophilic groups onto the ring nitrogen of nipecotic acid and guvacine, two known GABA uptake inhibitors, afforded potent, orally-active anticonvulsant drugs. A series of ...compounds is reported which explores the structure-activity relationships (SAR) in this series. Among the areas explored: side-chain SAR (aromatic-, heterocyclic-, and tricyclic-containing side chains) and modifications to the tetrahydropyridine ring. The benzhydrol ether-containing side chains afforded the most potent compounds with several exhibiting in vitro IC50 values for GABA uptake of < 1 microM (including 5, Table I; 37, 43, Table IV; and 44, Table V). Compound 44 was selected for extensive evaluation and subsequently progressed to Phase 1 clinical trials with severe adverse effects seen after single dose administration to humans.
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