25. 1. Place the Cs source from the gamma source kit
装置の要素
(E = 0.662 MeV) ~2 cm in front of the NaI(Tl) crystal.
2. Adjust the coarse and fine gain controls of the 575A
Amplifier so that the 0.662 MeV photopeak for 137Cs falls
at approximately channel 280. For the illustrations shown
in Figs. 3.2 and 3.3, the gain of the system has been set
so that 1 MeV falls at about channel 420 to 425. Since the
system is linear, 2 MeV would therefore fall at
approximately channel 840 to 850.
1. 鉛遮蔽
3. Accumulate the 137Cs spectrum for a time period long
波高
enough to determine the peak position. Fig. 3.2 shows a
typical 137Cs spectrum that has been plotted. Although Fig. 3.3. NaI(Tl) Spectr
these spectra are usually plotted on semilog graph paper,
the figures shown in this experiment are plotted on linear EXERCISE
2. 電気信号2, and 3 in Table 3.1.
paper to point out some of the features of the spectra. a. Plot both the 137Cs and 60Co spe
パルス b. From items 1, 2, and 3 in Table
4. After the 137Cs spectrum has been read from the MCA,
検
erase it and replace the 137Cs source with a 60Co source
頻度
from the gamma source kit. energy of the photopeaks vs. chan
5. Accumulate the spectrum for a period of time long shows this calibration for the data
出 3. 波高分析
enough for the spectrum to be similar to that in Fig. 3.3. and 3.3. If other calibration source
additional data points can be adde
6. Read out the MCA. entries in Table 3.1 will be filled ou
器 c. Use the energy calibration featu
compare the results with those fou
4. cpm→Bq/kg
WBCの場合は
5. Sv (Mondal)
私の守備範囲外
Fig. 3.2. NaI(Tl) Spectrum for Cs.
137 Fig. 3.4. Energy Calibration Curv