THEORY OF NEUTRON LOGGING I

Geophysics ◽  
1961 ◽  
Vol 26 (1) ◽  
pp. 27-39 ◽  
Author(s):  
C. W. Tittle
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Neutron Source ◽  
Epithermal Neutron ◽  
Diffusion Theory ◽  
Epithermal Neutron Flux ◽  
Slowing Down ◽  
Relative Response ◽  
Concentric Cylinders ◽  
Commercial Logging

An analytical theory of epithermal neutron logging is presented. One‐group diffusion theory is applied to the slowing down of neutrons from a point fast neutron source in infinite continuous media, in a single cylinder, and in concentric cylinders representing a fluid‐filled borehole and the surrounding formation. Numerical results are given for the epithermal neutron flux in a water‐filled hole six inches in diameter, passing through limestone of 10 percent or 30 percent porosity. Preliminary semiquantitative agreement is obtained with the relative response of a commercial logging instrument in the range of 10 to 100 percent porosity.

scholarly journals Double Layer Collimator for BNCT Neutron Source Based on 30 MeV Cyclotron

2017 ◽  
Vol 2 (3) ◽  
pp. 124
Author(s):  
Bilalodin Bilalodin ◽  
Kusminarto Kusminarto ◽  
Arief Hermanto ◽  
Yohannes Sardjono ◽  
Sunardi Sunardi
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Neutron Source ◽  
Double Layer ◽  
Thermal Neutron Flux ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux ◽  
Beryllium Target ◽  
Neutron Filter ◽  
Neutron Current

<span>A research of design of double layer collimator using </span><sup>9</sup><span>Be(p,n) neutron source has been conducted. The research objective is to design a double layer collimator to obtain neutron sources that are compliant with the IAEA standards. The approach to the design of double layer collimator used the MCNPX code. From the research, it was found that the optimum dimensions of a beryllium target are 0.01 mm in length and 9.5 cm in radius. Collimator consists of a D</span><sub>2</sub><span>O and Al moderator, Pb and Ni as a reflector, and Cd and Fe as a thermal and fast neutron filter. The gamma filter used Bi and Pb. The quality neutron beams emitted from the double layer collimator is specified by five parameters: epithermal neutron flux 1 ×10</span><sup>9</sup><span> n/cm</span><sup>2</sup><span>s; fast neutron dose per epithermal neutron flux 5 ×10</span><sup>13</sup><span> Gy cm</span><sup>2</sup><span>s; gamma dose per epithermal neutron flux 1×10</span><sup>13</sup><span> Gy cm</span><sup>2</sup><span>s; ratio of the thermal neutron flux of epithermal neutron flux 0; and the ratio of epithermal neutron current to total epithermal neutron 0.54.</span>

scholarly journals Beam Shaping Assembly Optimization for Boron Neutron Capture Therapy Facility Based on Cyclotron 30 MeV as Neutron Source

2018 ◽  
Vol 35 (3) ◽  
pp. 183-186
Author(s):  
Arief Fauzi ◽  
Afifah Hana Tsurayya ◽  
Ahmad Faisal Harish ◽  
Gede Sutresna Wijaya
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Epithermal Neutron ◽  
Beam Shaping ◽  
Neutron Capture Therapy ◽  
Epithermal Neutron Flux ◽  
Boron Neutron Capture ◽  
Beam Shaping Assembly

A design of beam shaping assembly (BSA) installed on cyclotron 30 MeV model neutron source for boron neutron capture therapy (BNCT) has been optimized using simulator software of Monte Carlo N-Particle Extended (MCNPX). The Beryllium target with thickness of 0.55 cm is simulated to be bombarded with 30 MeV of proton beam. In this design, the parameter regarding beam characteristics for BNCT treatment has been improved, which is ratio of fast neutron dose and epithermal neutron flux. TiF3 is replaced to 30 cm of 27Al as moderator, and 1.5 cm of 32S is combined with 28 cm of 60Ni as neutron filter. Eventually, this design produces epithermal neutron flux of 2.33 × 109, ratio between fast neutron dose and epithermal neutron flux of 2.12 × 10-13,ratio between gamma dose and epithermal neutron flux of 1.00 × 10-13, ratio between thermal neutron flux and epithermal neutron flux is 0.047, and ration between particle current and total neutron flux is 0.56.

scholarly journals Characteristics of Thermal Neutron Flux Distribution in a Phantom Irradiated by Epithermal Neutron Beam from Double Layer Beam Shaping Assembly (DBSA)

2019 ◽  
Vol 62 (3) ◽  
pp. 167-173
Author(s):  
Bilal Odin ◽  
Gede Bayu Suparta ◽  
Arief Hermanto ◽  
Dwi Satya Palupi ◽  
Yohannes Sardjono ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Double Layer ◽  
Neutron Beam ◽  
Epithermal Neutron ◽  
Beam Shaping ◽  
Epithermal Neutron Flux ◽  
Epithermal Neutrons ◽  
Beryllium Target ◽  
Beam Shaping Assembly

A simulation study on the Double-layer Beam Shaping Assembly (DBSA) system has been carried out. This study used fast neutron beam resulting from reactions of 30 MeV protons with beryllium target. The MCNPX code was utilized to design the DBSA and the phantom as well as to calculate neutron flux on the phantom. The distribution of epithermal neutron flux and gamma in the DBSA and phantom were computed using the PHITS code. The spectrum of radiation beams generated by the DBSA shows the characteristics that the typical epithermal neutron flux of 1.0 x109 n/(cm2.s), the ratio of epithermal to the thermal and fast neutron flux of 344 and 85, respectively and the ratio of gamma dose to the epithermal neutron flux of 1.82 x 10-13 Gy.cm2. The test of epithermal neutron beams irradiation on the water phantom shows that epithermal neutrons are thermalized and penetrate the phantom up to 12 cm in depth. The maximum value of neutron flux is 1.1 x 109 n/(cm2.s) at a depth of 2 cm in phantom.  

The Mismatch of Thermal and Epithermal Neutron Flux

1967 ◽  
Vol 29 (2) ◽  
pp. 299-302 ◽  
Author(s):  
K. B. Cady ◽  
G. J. Kirouac ◽  
J. J. McInerney
Keyword(s):  
Neutron Flux ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux

scholarly journals A Design of Boron Neutron Capture Therapy for Cancer Treatment in Indonesia

2016 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Yohannes Sardjono ◽  
Susilo Widodo ◽  
Irhas Irhas ◽  
Hilmi Tantawy
Keyword(s):  
Neutron Flux ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Neutron Generator ◽  
Epithermal Neutron ◽  
Research Reactor ◽  
Neutron Capture Therapy ◽  
Epithermal Neutron Flux ◽  
Boron Neutron Capture ◽  
Compact Neutron Generator

Boron Neutron Capture Therapy (BNCT) is an advanced form of radiotherapy technique that is potentially superior to all conventional techniques for cancer treatment, as it is targeted at killing individual cancerous cells with minimal damage to surrounding healthy cells. After decades of development, BNCT has reached clinical-trial stages in several countries, mainly for treating challenging cancers such as malignant brain tumors. The Indonesian consortium of BNCT already developed of the design BNCT for many cases of type cancers using many neutron sources. The main objective of the Indonesian consortium BNCT are the development of BNCT technology package which consists of a non nuclear reactor neutron source based on cyclotron and compact neutron generator technique, advanced boron-carrying pharmaceutical, and user-friendly treatment platform with automatic operation and feedback system as well as commercialization of the BNCT though franchised network of BNCT clinics worldwide. The Indonesian consortium BNCT will offering to participate in Boron carrier pharmaceuticals development and testing, development of cyclotron and compact neutron generators and provision of neutrons from the 100 kW Kartini Research Reactor to guide and to validate compact neutron generator development. Studies were carried out to design a collimator which results in epithermal neutron beam for Boron Neutron Capture Therapy (BNCT) at the Kartini Research Reactor by means of Monte Carlo N-Particle 5 (MCNP5) codes. Reactor within 100 kW of output thermal power was used as the neutron source. The design criteria were based on the IAEA’s recommendation. All materials used were varied in size, according to the value of mean free path for each. Monte Carlo simulations indicated that by using 5 cm thick of Ni as collimator wall, 60 cm thick of Al as moderator, 15 cm thick of 60Ni as filter, 1,5 cm thick of Bi as "-ray shielding, 3 cm thick of 6Li2CO3-polyethylene as beam delimiter, with 3-5 cm varied aperture size, epithermal neutron beam with minimum flux of 7,8 x 108 n.cm-2.s-1, maximum fast neutron and "-ray components of, respectively, 1,9 x 10-13 Gy.cm2.n-1 and 1,8 x 10-13 Gy.cm2.n-1, maximum thermal neutron per epithermal neutron ratio of 0,009, and beam minimum directionality of 0,72, could be produced. The beam did not fully pass the IAEA’s criteria, since the epithermal neutron flux was still below the recommended value, 1,0 x 109 n.cm-2.s-1. Nonetheless, it was still usable with epithermal neutron flux exceeded 5 x 108 n.cm-2.s-1. When this collimator was surrounded by 8 cm thick of graphite, the characteristics of the beam became better that it passed all IAEA’s criteria with epithermal neutron flux up to 1,7 x 109 n.cm-2.s-1. it is still feasible for BNCT in vivo experiment and study of many cases cancer type i.e.; liver and lung curcinoma. In this case, thermal neutron produced by model of Collimated Thermal Column Kartini Research Nuclear Reactor, Yogyakarta. Sodium boroncaptate (BSH) was used as in this research. BSH had effected in liver for radiation quality factor as 0.8 in health tissue and 2.5 in cancer tissue. Modelling organ and source used liver organ who contain of cancer tissue and research reactor. Variation of boron concentration was 20, 25, 30, 35, 40, 45, and 47 $g/g cancer. Output of MCNP calculation were neutron scattering dose, gamma ray dose and neutron flux from reactor. Given the advantages of low density owned by lungs, hence BNCT is a solid option that can be utilized to eradicate the cell cancer in lungs. Modelling organ and neutron source for lung carcinoma was used Compact Neutron Generator (CNG) by deuterium-tritium which was used is boronophenylalanine (BPA). The concentration of boron-10 compound was varied in the study; i.e. the variations were 20; 25; 30; 35; 40 and 45 μg.g-1 cancer tissues. Ideally, the primary dose which is solemnly expected to contribute in the therapy is alpha dose, but the secondary dose; i.e. neutron scattering dose, proton dose and gamma dose that are caused due to the interaction of thermal neutron with the spectra of tissue can not be simply omitted. Thus, the desired output of MCNPX; i.e. tally, were thermal and epithermal neutron flux, neutron and photon dose. The liver study variation of boron concentration result dose rate to every variation were0,042; 0,050; 0,058; 0,067; 0,074; 0,082; 0,085 Gy/sec. Irradiation time who need to every concentration were 1194,687 sec (19 min 54 sec);999,645 sec (16 min 39 sec); 858,746 sec (14 min 19 sec); 743,810 sec (12 min 24 sec); 675,156 sec (11 min 15 sec); 608,480 sec (10 min 8 sec); 585,807sec (9 min 45 sec). The lung carcinoma study variations of boron-10 concentration in tissue resulted in the dose rate of each variables respectively were 0.003145, 0.003657, 0.00359, 0.00385, 0.00438 and 0.00476 Gy.sec-1 . The irradiated time needed for therapy for each variables respectively were 375.34, 357.55, 287.58, 284.95, 237.84 and 219.84 minutes.

Determination of thermal neutron flux distribution at the rotary rack served for elemental concentration analysis using the k0-INAA method

2021 ◽  
Vol 10 (1) ◽  
pp. 11-20
Author(s):  
Tho Nguyen Thi ◽  
Anh Tran Tuan ◽  
Cuong Trinh Van ◽  
Doanh Ho Van ◽  
Duong Tran Quoc ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Flux Distribution ◽  
Thermal Neutron Flux ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux ◽  
Irradiation Position ◽  
Neutron Flux Distribution ◽  
Sample Irradiation

The accuracy of elements concentration determination using the k0-standardization method directly depends on irradiation and measurement parameters including Non-1/E epithermal neutron flux distribution shape α (ϕ epi ≈1/E1+α ) , thermal-to-epithermal neutron flux ratio f, efficiency ε, peak area… In the case of the irradiation position at the rotary rack of the Dalat Nuclear Research Reactor (DNRR), the difference of thermal neutron flux between the bottom (3.54x1012 n.cm-2.s-1) and the top (1.93x1012 n.cm-2.s-1) of the 15 cm aluminum container is up to 45%. Therefore, it is necessary to accurately determine above-mentioned parameters in the sample irradiation position. The present paper deals with the determination of the distribution of thermal neutron flux along the sample irradiation container by using 0.1% Au–Al wire activation technique. The thermal neutron flux was then used to calculate the concentration of elements in the Standard Reference Material 2711a and SMELS type III using k0-INAA method at different positions in the container. The obtained results with the neutron flux correction were found to be in good agreement with the certified values. In conclusion, the proposed technique can be applied for activation analyses without sandwiching flux monitors between samples during irradiations.

Investigation of Thermal and Epithermal Neutron Flux Distributions in Universal Nuclear Icebreaker Fuel Assemblies

Atomic Energy ◽  
2017 ◽  
Vol 121 (6) ◽  
pp. 389-396 ◽  
Author(s):  
O. B. Samoilov ◽  
V. I. Alekseev ◽  
V. Yu. Galitskikh ◽  
A. V. Belin ◽  
A. N. Zaglyadnov ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux ◽  
Fuel Assemblies
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