RADIOISOTOPES

Development of Simple Passive Neutron Dosimeter with Cylindrical Acrylic Resin Moderator Using Termoluminescent Detector

Yoshihiro OGAWA, Takafumi SENOO

2005 Volume 54 Issue 8 Pages 287-295
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.287

JOURNAL FREE ACCESS

Show abstractHide abstract

In comparison with direct readings of neutron dose rate by Sievert meter, a passive thermal neutron detector inserted into moderator shows possibilities of not only intermediate and fast neutron measurement but also accumulated dose measurement during long term monitoring periods in low level neutron dose rate. Here, simple passive neutron dosimeter (10 cm diameter and 15 cm length) consisting of stratified acrylic resin disc (10 cm diameter and 0.5 cm thickness) which inserted a pair of the thermoluminescent elements, CaSO₄ : Tm+⁶LiF and CaSO₄ : Tm+⁷LiF, as a thermal neutron detector, was produced. Performance and features of the neutron dosimeter were examined in various moderating neutron fields of ²⁵²Cf and Pu-Be neutron sources. In addition, the response function of neutron dosimeter from 10^-9 MeV to 20 MeV was made and neutron energy spectrum was estimated with adjustment method using the reading values of neutron dosimeter. Finally, accuracy on neutron dose evaluation method and applicability of the neutron dosimeter to neutron monitoring were investigated
The neutron energy spectra that were adjusted with the response function and the reading values of neutron dosimeter were reproduced for those of ²⁵²Cf and Pu-Be neutron sources at a good accuracy. The neutron doses evaluated based on estimated neutron energy spectra showed the neutron dose response indicating from 1.06×10^-4 to 1.45×10^-4 Gy/Sv, and (1.26±0.14) ×10^-4 Gy/Sv on an average according to various moderating neutron fields, which was almost equal to the Sievert meter. From the results obtained, the present simple passive neutron dosimeter was found to be a useful neutron detector for routine neutron monitoring for the range of neutron energy from several MeV to thermal energy in various radiation fields.

View full abstract

Download PDF (863K)
Optimal Measurement Condition of Basis Weight Gauge Using X-ray Generated with Tube Voltage Lower than 5 kV

Takahiro YAMADA, Shigeru TAKATA, Takashi SUZUKI

2005 Volume 54 Issue 8 Pages 297-304
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.297

JOURNAL FREE ACCESS

Show abstractHide abstract

As the recently developed low energy X-ray generator (10 kV) enabled us to compose an X-ray basis weight measurement, we devised the basis weight gauge for paper and evaluated its performance in terms of the resolutions of the basis weight in various conditions i.e., tube voltage, tube current, the distance between the X-ray source and the detector. The optimal conditions of the basis weight for 22.4 g/m² paper were as follows, tube voltage : 2.5 kV, tube current : 0.4 mA, distance X-ray source, and the detector: 1 cm. Under these conditions, the resolution and the relative resolution were 0.33 g/m² and 1.4%, respectively. The optimum tube voltages for the basis weights below 130g/m² and 130-300 g/m² were 2.5 kV and 3.5 kV, respectively. The results show that the low energy X-ray (below 5 kV) is available for the precise measurement of basis weight.

View full abstract

Download PDF (706K)
Physiological Variation of Mineral Contents in Hair of Dairy Cow Analyzed by Means of PIXE

Yasuhiro AOKI, Sada ANDO, Akihisa YAMADA, Ryoji KOBAYASHI, Jianguo ZHA ...

2005 Volume 54 Issue 8 Pages 305-313
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.305

JOURNAL FREE ACCESS

Show abstractHide abstract

Hair samples were collected in May 2002 (12 cows), November 2002 (16 cows) and September 2003 (20 cows) from Holstein lactating cows that were given sufficient nutrition and were clinically healthy, and were analyzed by standard free, direct method of PIXE. The elements detected were S, K, Ca, Na, Mg, Zn, Br, Fe and Cu. Hair mineral levels generally seemed to be varied among cows and to differ remarkably compared with those reported for grazing beef cattle, probably due to differences of general feeding management and amount of feed intake. Except for K and Fe, significant seasonal fluctuations of mineral contents in hair were observed, showing that the mineral contents were lower in September and higher in May and November. In addition to the seasonal effect, Ca and Zn contents decreased with the increase of milk production level (fat corrected milk yield), Na contents decreased with the increase of body weight, and Mg contents decreased with the parity and increased with the increment of body fat accumulation (body condition score) . It is shown that the mineral contents in hair of high producing dairy cows are varied widely by physiological factors.

View full abstract

Download PDF (905K)
Measurement of ²²²Rn Concentrations in Surface Water in Northeast Thailand

Hiromasa HAMADA, Somsak SUKCHAN, Mahithon PUTISO

2005 Volume 54 Issue 8 Pages 315-320
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.315

JOURNAL FREE ACCESS

Show abstractHide abstract

In northeast Thailand, salinization caused by the discharge of salty groundwater is a serious problem. Locations where groundwater flows into surface water must be identified before measures against salinization can be taken. Radon-222 (²²²Rn) is a useful indicator for determining areas of groundwater discharge. We measured ²²²Rn concentrations in surface waters in the region and found that groundwater flows into streams and lakes in low-elevation areas (below 180 m) . Our results agree with the results of published simulations of groundwater flow.

View full abstract

Download PDF (419K)
Major Ionic Components in Atmospheric Depositions Collected along the Altitudinal Gradient of Mt. Emei, Sichuan, China

Naofumi AKATA, Fumitaka YANAGISAWA, Hitoshi KAWABATA

2005 Volume 54 Issue 8 Pages 321-327
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.321

JOURNAL FREE ACCESS

Show abstractHide abstract

We collected atmospheric depositions along the altitudinal gradient on Mt. Emei, China. This study was intended to estimate the deposition rate of the major ionic components by below-cloud scavenging using their altitude distribution of Mt. Emei, which is located in a region of severe air pollution. The precipitation rate tends to increase because of cloud deposition (1500-2500 m) . The atmospheric depositions collected at St. 12, 13 and 17 seemed to evaporate from the altitude distribution pattern of δD and precipitation rate. The deposition flux of ionic components increased at lower altitudes, without dependence on precipitation rate. The main ionic components that influenced atmospheric deposition in this region were SO₄^2-, NO₃^-, NH₄⁺ and Ca²⁺. We estimated the increase rate in ionic components by below-cloud scavenging based on the altitude distribution of ion concentrations, except NH₄⁺, which did not show good correlation with the first approximation. Respective rates of increase in SO₄^2-, NO₃^- and Ca²⁺ were 5.33, 1.36 and 9.51 μeq·L^-1, when raindrops fell 100m.

View full abstract

Download PDF (662K)
Evaluation of Entropy-based Image Co-registration Techniques for Brain Perfusion SPECT

Takashi YOKOI, Akihiro TAKAKI, Tsutomu SOMA, Katsunori YOSHIOKA

2005 Volume 54 Issue 8 Pages 329-336
Published: August 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.329

JOURNAL FREE ACCESS

Show abstractHide abstract

We examined image co-registration techniques based on mutual information (MI) and normalized mutual information (NMI) to registrate two SPECT images with localized differences in brain activity. Simulations were performed by 100 trials with the random initial mismatch of ±20° and ±45 mm for a normal perfusion model (NRM) and a pathological perfusion model with a hemisphere defect (HSD) . In the HSD, activity in the defect region was reduced to be 75% (HSD_75%), 50% (HSD_50%), and 25% (HSD_25%) of normal value. In the MI-based registration for the NRM and NRM dataset, no biases were observed (≤-0.06°, ≤0.06 mm) and the SDs were very small (≤0.07°, ≤0.04 mm) . In the registration for the NRM and HSD dataset, the biases were slightly larger (≤-0.18°, ≤0.34 mm for HSD_75%, ≤-0.23°, ≤=0.45 mm for HSD_50%, ≤-0.23°, ≤0.18 mm for HSD_25%) in comparison with the results of registration for the NRM and NRM dataset. The accuracy of the NMI was almost identical to that of the MI. The entropy-based registration techniques are relatively unaffected by localized differences in brain activity.

View full abstract

Download PDF (2615K)
Instruments for Radiation Measurement in Life Sciences (4) . IX. ADME Studies of Labeled Pharmaceutics in Human

—Overview and Current Development in Japan—

Eiichi NAKAJIMA

2005 Volume 54 Issue 8 Pages 337-345
Published: August 15, 2005
Released on J-STAGE: July 21, 2010

DOIhttps://doi.org/10.3769/radioisotopes.54.337

JOURNAL FREE ACCESS

Download PDF (1186K)
Instruments for Radiation Measurement in Life Sciences (4) . At the End of the AMS Series

Norio KURIHARA

2005 Volume 54 Issue 8 Pages 347-348
Published: August 15, 2005
Released on J-STAGE: July 21, 2010

DOIhttps://doi.org/10.3769/radioisotopes.54.347

JOURNAL FREE ACCESS

Download PDF (152K)
Estimation of Total Amount of Long-lived Fission Products Discharged from Nuclear Fuel Reprocessing Facilities

Shoichi TACHIMORI

2005 Volume 54 Issue 8 Pages 349-358
Published: August 15, 2005
Released on J-STAGE: July 21, 2010

DOIhttps://doi.org/10.3769/radioisotopes.54.349

JOURNAL FREE ACCESS

Download PDF (6911K)

Register with J-STAGE for free!