STUDY ON MODERATIORS OF SMALL—SIZE NEUTRON RADIOGRAPHY INSTALLATIONS WITH NEUTRON TUBE AS SOURCE

Calculation of moderator analogues for 14 MeV neutrons as source were made at a IBM/PC AT computer using TAMAKER-ANISN program and 46 groups(25 neutron groups,21 photon groups) UW cross section data.The intensifying effect of lead and natural uranium for moderating 14 MeV neutrons is confirmed.Adopting proper structure of the moderator,the intensifying factor M( times) may be larger than 3.Using lead and naural uranium in sub-critical assemblies (or cell boosters),with 14 Me neutrons as source,with the same dimension as that of abouve,the intensifying effect is also confirmed.With a proper structure of sub-critical assembly,the intensifying factor M may be close to or even larger than(1-k)^-1 where k is the effective multiplication factor.     

THE STUDY OF NEUTRON EMISSIONS IN 585 MeV PROTONS ON ~(56)Fe WITH QMD

The analyses of intermediate energy nucleon-nucleus collisions are com-monly based on the frame work of intranuclear cascade model.This model treats the reaction machanism in terms of a succession of nucleon-nucleon col-lisions with particles emitted at the various stages as the projectile energy is progressively dissipated in the target nuclei.     

THE STUDY OF PROMPT NEUTRON SPECTRA OF ~(238)U FISSION INDUCED BY FAST NEUTRON

The preliminary measurements of prompt neutron time-of-flight spectraof U fission induced by 11 MeV neutrons were carried out at HI-13 TandemVan de Graaff Accelerator Laboratory in 1989.The exprimental set up isshown in Fig.1.     

PROGRESS ON EVALUATION OF NEUTRON NUCLEAR DATA AT PEKING UNIVERSITY

INTRODUCTION The program of evaluation of neutron nuclear data is contracted andcooperated with Chinese Nuclear Data Center(CNDC).The recent contractwill be finished in the year as follows:1) Evaluation of Complete Neutron Data for ~(238)U:The pointwise data in theenergy range of 20 keV to 20 MeV and the adjusting of all reaction channels(Tang Guoyou,Cao Wentian,Bao Shanglian).[The data of reaction channels     

MEASUREMENT OF NEUTRON SPECTRA FROM THICK Be TARGET BOMBARDED WITH DEUTERONS

ＭＥＡＳＵＲＥＭＥＮＴＯＦＮＥＵＴＲＯＮＳＰＥＣＴＲＡＦＲＯＭＴＨＩＣＫＢｅＴＡＲＧＥＴＢＯＭＢＡＲＤＥＤＷＩＴＨＤＥＵＴＥＲＯＮＳＷａｎｇＸｉａｏｚｈｏｎｇ（王效忠）；ＢａｉＸｉｘｉａｎｇ（白希祥）；ＬｉＡｎｌｉ（李安利）；ＬｉｕＷｅｉｐｉｎｇ（柳...     

EVALUATION OF NEUTRON INDUCED DATA ON ~(19)F

INTRODUCTION Flurine is an important material in fusion reactor.The neutron induced da-ta on F are very useful in fusion reactor design and other nuclear engineeringapplication.The evaluation in ENDF/B-5 for ~(19)F was finished by Larson etal.in 1979.Since then,several new measurements are available.InENDF/B-5 evaluation,energy distribution of the recoil nuclei was notgiven and the theory calculation was not used to give the γ-ray productiondata to ensure the eneray balance.     

A STUDY ON THE SAND OF FLAMING MOUNTAIN

A sand sample collected at the foot of Flaming Mountain was studied further. On the basis of the change in the relative intensity after heat treatment, one of the sextets observed in its Mossbauer spectrum at liquid nitrogen temperature was ascribed to goethite. This result provides a useful information on the geological history of the region where the mountain is located.     

SMALL ANGLE SCATTERING CROSS SECTIONS OF 14.8 MeV NEUTRON FOR Fe,Ni AND Cr

Fe,Ni and Cr are the important structural material nuclides for fusion ap-plication.There is a forword peak in the angular distribution for about 14 MeVneutron.So the precision of the differential scattering cross sections at smallangle region has strong influence on the total scattering cross section.The ex-perimental data of scattering cross sections at small angle are very scarce for Feand Ni and have not published yet for Cr.     

EVALUATION OF NEUTRON DATA ON ~3He FOR CENDL—2

INTRODUCTION The neutron cross sections of ~3He are of importance in nuclear techniqueand nuclear engineering.The large,nearly 1/v(n,p)cross section of ~3He hasbeen used as a standard cross section.Moreover,this process is an importanttriton-making reaction.     

STUDY ON LUNG DOSE FOR DIFFERENT ANIMALS BY INHALATION OF SHORT－LIVED RADON DAUGHTERS

ＳＴＵＤＹ　ＯＮ　ＬＵＮＧ　ＤＯＳＥ　ＦＯＲ　ＤＩＦＦＥＲＥＮＴ　ＡＮＩＭＡＬＳ　ＢＹ　ＩＮＨＡＬＡＴＩＯＮ　ＯＦ　ＳＨＯＲＴ－ＬＩＶＥＤ　ＲＡＤＯＮ　ＤＡＵＧＨＴＥＲＳＬｉＳｕｙｕｎ，ＺｈａｎｇＳｈｅｎｇｈｕｉａｎｄＨｏｕＨａｉｑｕａｎ（Ｃｈｉｎａ...     

小型中子照相装置慢化体的研究

文章研究用混合D-T束密封中子发生器进行中子照相的14MeV中子慢化问题,提出了用高密度聚乙烯和铅相结合慢化14MeV中子的结构,实验证实,在源附近加一定厚度的铅层可以把热化比降低三分之一左右。这种结构的热化比是用水慢化14MeV中子的热化比的1/2—1/3。慢化体加铅后对中子束镉比的影响并不很大。     

一种中子管用的Al2O3自生靶

一、引言采用自生靶是提高中子管性能的首要措施,而自生靶的材料选择和工艺处理方法对其性能有很大影响。菲利普等公司用蒸发到银基片的钛膜作为自生靶材料;我们对氚-钛靶和钛膜自生靶也做过一些实验。但这种钛膜靶会因溅射损失而影响寿命。我们在实验中还发现,当工作束流较大,靶温升高时,钛层中的气体会迅速逸出,使管内气压难     

碘的微堆超热中子活化法测定

对碘的超热中子活化分析法进行了研究，利用该方法在微堆上测定了血液１食品及土壤中的碘含量，计算了该方法对全血及血清中碘的探测下限。     

中子管特性及其工作状态的调整

本文通过对国产冷阴极Penning离子源中子管特性的研究及工作原理的分析,说明加速电压、阳极电压、储存器电流与中子产额的关系。提出中子管的特性曲线并对调整、控制中子产额的方案给予评价。     

镅-铍中子源事故受照人员的细胞遗传学观察

在一起镅—铍中子源事故中,有14人受到内外混合照射。照后初期对6名受照者进行了染色体畸变分析并估算其生物剂量。结果生物剂量与理物剂量相当接近,盗源者生物剂量为96.3～127.8mGy,物理剂量为121mGy,其他人员生物剂量和物理剂量在1～30mGy之间。 在事故后一年半时,用稳定性畸变分析方法,分析了14例受照者的染色体畸变,结果受照组仍明显高于对照组。     

插入型中子水分计响应的研究

文章叙述了采用三组扩散理论模型研究了插入型中子计测量球团料水分的响应问题。对不同密度和氯分的料进行了数值计算和实验标定。在4—14wt%水分范围内,计数率随水分增大而线性增大。密度变化1%对水分测量值的影响为0.12wt%,氯分变化1wt%的影响为2wt%。理论计算结果经效率修正后与实验测量结果相符合。     

热中子辐照提高YBCO和GdBCO超导材料Jc的研究

利用重水反应堆水平孔道热中子对熔融织构生长(Melt-Textured Growth)的YBa_2Cu_3O_(7-y)和GdBa_2Cu_3O_(7-y)超导材料进行辐照研究。前者共8个样品,热中子注量为3.7×10~(11)-1.4×10~(17)cm~(-2);后者共6个样品热中子注量为5.2 ×10~(13)-4.7×10~(16)cm~(-2)。样品辐照前后,用移动样品磁强计测量其磁滞回线并推算出临界电流密度进行比较。YBCO结果表明,当热中子注量大于10~(17)cm~(-2)时,J_c可增加一倍以上。GdBCO样品也有明显增加。在上述热中子注量范围内,J_c值增量随辐照注量增加而增加,并且高场时增加值比低场时更大。这可能是由于随着辐照注量增加,缺陷增多,钉扎中心密度增加,两钉扎中心的相对距离减小。这更有利于高场下的钉扎作用。