Nal scintillator detectors

The concrete block walls of the cell housing the generator tube and associated components are 1.7 meters thick. The facility also includes a Kaman Nuclear dual-axis rotator assembly for simultaneous transfer and irradiation of reference and unknown sample, and a dual Na iodide (Nal) scintillation detector system designed for simultaneous counting of activated samples. Automatic transfer of samples between load station to the rotator assembly in front of the target, and back to the count station, is accomplished pneumatically by means of two 1.2cm (i.d.) polyethylene tubes which loop down at both ends of the system and pass underneath the concrete shielding thru a pipe duct. Total one-way traverse distance for the samples is approx 9 meters. In performing quantitative analysis for a particular element by neutron activation, the usual approach is to compare the count rates of an unknown sample with that of a reference standard of known compn irradiated under identical conditions... 

A sealed-tube neutron generator, utilizing the deuterium-tritium reaction is the source of fast (14 MeV) neutrons, and a 8 x 3 1 Nal scintillation detector, with three optically coupled photomultipliers, is used to measure the >ray signal... 

Insulin delivery rate was determined by following the increase in 125I-insulin concentration in a 2-mL downstream reservoir. The reservoir was connected via a siphon to a test tube that fit into the sampling well of a Nal scintillation detector. A 1-mL sample of the downstream solution was taken by appropriate manipulation of the siphon arm heights. The detector was connected to an Eberline MS-2 Scaler (Datamex Ltd.). The insulin reservoir solution contained 100 U/mL Toronto insulin and approximately 0.5 xCi/mL of 125I-insulin (Amersham-Searle). 

Nal scintillation detectors are typically used to detect gamma rays. Up to about 10,000 counts/s, the signal is linear, and above this level dead-time or pile-up becomes noticeable for a 7.6 cm diameter unit. (Background radiation is typically less than 100 counts/s). Lead collimaters provide adequate shields to narrow the... 

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