NEUTRON RESPONSE FUNCTION OF BONNER SPHERE SPECTROMETER WITH 6 LiI(Eu) DETECTOR.The neutron response function of 6 LiI(Eu) 0",2",3",5",8",10",12

ABSTRAKPekerja radiasi wajib melakukan pemantauan dosis radiasi untuk mengurangi dampak radiasi pengion pada tubuh. Pemerintah melalui BAPETEN menetapkan dosis ekivalen maksimum untuk pekerja sebesar 20 mSv/tahun. Salah satu alat pantau personal yang banyak dipakai adalah TLD-700 (khususnya untuk radiasi gamma). Dosis ekivalen pada tubuh pekerja radiasi untuk kedalaman 10 mm (Hp(10)) dapat diperkirakan melalui pendekatan simulasi MCNPX. Untuk melakukan simulasi dibutuhkan input model geometri yang disesuaikan dengan geometri pada eksperimen. Hasil simulasi pada posisi sumber tegak lurus diperoleh laju dosis 8,565mSv/jam, yang menunjukan perbedaan sebesar 1,5% terhadap hasil eksperimen, sehingga dosis Hp (10) ABSTRACTRadiation workers are compulsory to monitoring radiation dose for reduce the effects of ionizing radiation on the body. Government through similar BAPETEN maximum dose for radiation workers is 20 mSv/year. One of the personal monitoring tool that is widely used is the TLD-700 (specially for gamma radiation). The equivalent dose to the worker's body to a depth of 10mm (Hp(10)) able to be predicted from a simulation approach MCNPX. To simulation needed input model of geometry which adapted to the geometry experiments. The simulation results at the source position vertical to the dose rate is obtained 8,565mSv/h, which shows a difference of 1.5% on the results of the experiment, so the Hp(10) dose can be determined. This experiment able to simulated for contamination source 137 Cs on the floor position unable to be done experimentely contamination source. Estimation through simulation, the dose rate on the floor at 14.920 mSv/h. The results showed the difference of dose rate through dose rate 75% vertical source larger than the vertical direction. According to the result need to be calibration TLD-700 for the source position from the bottom. Because the greater the dose rate (from below), the greater the Hp(10) dose is received. With the result clear that considerable potential MCNPX used to estimate personal Hp(10) dose for radiation workers, specially in relation to the case of a radiation accident.

Telah dilakukan pengukuran spektrum neutron pada tabung berkas neutron fasilitas radiografi neutron reaktor G.A Siwabessy. Pengukuran dilakukan untuk mengkonfirmasi adanya faktor penyebab menurunnya kualitas ketajaman citra hasil dari radiografi. Pengukuran spektrum neutron dilakukan menggunakan single sphere spectrometer (SSS) dengan tujuh detektor keping emas. Tampilan spektrum neutron dari konversi aktivitas detektor SSS dilakukan menggunakan software UMG 3.3, adapun fungsi respon detektor SSS dihitung menggunakan software MCNPX. Berdasarkan hasil pengukuran diperoleh spektum neutron didominasi termal dengan fluks termal 6,14×106 neutron cm-2s-1, epitermal 1,18×106 neutron cm-2s-1, dan neutron cepat 3,37×106 neutron cm-2s-1. Hasil pengukuran spektrum tersebut mengkonfirmasi bahwa terjadi penurunan fluks neutron termal di ujung tabung berkas neutron radiografi (dari 9,2×106 neutron cm-2s-1), sehingga hal ini bisa menjadi salah satu sebab penurunan kualitas ketajaman citra radiografi.

In the development of low-medium energy photon calibration facilities we have simulated several types of gamma irradiator collimator materials with ISO 4037-1 design connected to the output beam spectrum and the resulting kerma. Four types of collimator material, namely Al, Fe, Pb, and WCu have been simulated with gamma radiation sources 241Am, 57Co, 137Cs, and 60Co. Simulations were carried out using the Monte Carlo method with the PHITS computer program. Based on the comparison of air kerma produced, collimators made from Al are suitable for gamma sources 241Am, Fe material for gamma sources 57Co, and Pb material for sources 137Cs and 60Co.