Proceedings - Viện Vật lý

Advances _________________________________________________________________________________in Optics, Photonics, Spectroscopy and Applications. Aug. 2006, Cantho, Vietnam(ZnS:Ag) and there from studying pulse height distribution for alpha particles incidenton the scintillator. These data will be necessary to design of our home made TASCdevice; (2) some results of radioactivity and annual dose of some ancient ceramic inMy Son,Viet nam, using our homemade TSAC.2.1. Sample preparation2. Material and methodSamples were bricks and ceramic sherds and surrounding burial soil from ancienttowers in My son, Central of Viet nam . About 1 g of sample was ground into powderform using pestle and mortar, then spread evenly on the screen. A thick layer of sampleis then in direct contact with the ZnS screen, its thickness is thicker than the range Rfor the most energetic alpha emitter of the series -49.6m and 40m, Th and U,respectively [1]. About 0.2 of powdered sample is enough to get geometry2.2. Calibration standardThe standard chosen was S329, (kindly given by TL dating laboratory - BicoccaMilan University) a standard sand that has been accurately analyzed by several nucleartechniques and of course it could meet some other demands (similarity of alphaspectra, the average Z and A, grain size, radioactive equilibrium...). S329 gives apredicted count-rate of 15 counts per minute.2.3. Zinc sulphide screenInc.Mylar screen, diameter: 44mm, supplied by Daybreak Nuclear & Medical system,2.4. InstrumentationZnSholder42 mmsamplePMTPreAmpPulseshapingDiscriminatorCounter(MC)PhotomultipliermultiplierTSACDigitalStorageOscilloScopeFig 1. Experiment set up for TSAC techniqueDisplay(LCD)149