Xe~(23+)离子辐照Al_2O_3的光谱特性

本工作研究460 keV、3 MeV和308 MeV Xe23+辐照Al2O3单晶样品的光致发光特性。从经过460 keV Xe23+辐照后样品的光致发光测试结果可看到,波长为380、413和450 nm的发光峰明显增强,在390和564 nm处出现了新的发光峰。从3 MeV的Xe23+辐照后样品谱的变化可看到,在较低剂量条件下,516 nm(2.4 eV)和564 nm(2.2 eV)处的发光峰随辐照剂量增加而增强,且当剂量增到1×1016cm-2时,564 nm处的发光峰消失,只有516 nm(2.4 eV)处的发光峰较强。从308 MeV Xe23+辐照后样品的光致发光谱中可看到,357 nm(3.47 eV)和516 nm(2.4 eV)处的发光峰随着剂量增加明显增强。辐照后样品的FTIR谱显示:波数在460~510 cm-1和630 cm-1附近的吸收是Al2O3振动模式,经离子辐照后,吸收带展宽;1 000~1 300 cm-1间为Al—O—Al桥氧键的伸缩振动模式,高能辐照后的吸收带向低波数方向移动。

~(22)Na(p,γ)~(23)Mg反应的实验研究

讨论了目前有关2 2 Na(p ,γ) 2 3Mg反应的实验研究工作 ,结合兰州放射性束流线上的放射性束流2 3Al的β+延发质子衰变实验的测量结果 ,给出了2 3Al延发衰变的质子能谱 ,并比较了近期实验给出的相关能级的自旋、宇称值 ,正是由于这种自旋、宇称和能级部分宽度的不确定性 ,导致了反应率计算的不确定性 .计算了同位旋相似态的共振强度 .对于测量到的新的延发衰变能级Ed =8.91 6MeV ,由于没有相应的能级宽度值 ,实验仅给出其相对共振强度值

~(230)Acβ-延发裂变概率的测定

由60MeV/μ18O离子照射天然钍靶所引起的232Th-2p反应产生230Ra,通过放射化学分离方法从被照射的靶中提取出镭元素并制成薄源,经230Ra230Ac得到230Ac.用云母裂变径迹探测器和PHGeγ射线探测器对来自源中的裂变碎片和γ谱进行记录和测量,借助于所测得的两个裂变事件和γ谱,鉴别了β-延发裂变核230Ac,得到了它的β-延发裂变概率为（1.19±0.85）×10-8.

~(230)Ac β延发裂变

本文叙述了远离beta稳定线新核素合成尤其是beta延发裂变研究的重要意义,介绍了beta延发裂变先驱~(230)Ac的搜索及其延发裂变几率的测定。

寻找~(230)U的集团衰变

使用35MeV质子轰击ThO2,通过232Th(p,3n)230Pa反应产生目标核。用放射化学分离法从靶材料和其它反应产物中分离Pa,制备薄的Pa源。用HPGe探测器测量Pa源的γ能谱,使用聚乙烯对苯二酸酯(PTEP)固体径迹探测器记录重离子径迹,首次发现了230U发射22Ne离子的稀有衰变模式,并获得了它相对于α粒子发射的分支比为(1.3±0.8)×10-14。

~(230)Ac的β延发裂变

用 6 0MeV/u18O离子轰击ThO2 ,通过多核子转移和靶的耗散碎裂反应产生2 3 0 Ra。利用放射化学分离技术 ,将镭与钍及其它反应产物分离并制备成薄镭源。该源对云母裂变径迹探测器暴光 ,用高纯锗探测器测量镭源的γ活度 ;用氢氟酸溶液对云母箔进行蚀刻 ,使用光学显微镜观测云母箔中的裂变径迹。首次观测到了可能来自2 3 0 Acβ延发裂变的两个事件 ,获得它的 β延发裂变几率为 (1 19± 0 85 )× 10 -8。

~(23)Al 的β~+延发质子测量

利用ＴＯＦ－ Ｅ和０°注入探测器的方法，鉴别并测量了２３Ａｌβ＋延发质子衰变能谱，通过精密脉冲发生器和计数器测得２３Ａｌ的半衰期 Ｔ１／２＝（４７６±４５）ｍｓ．实验中重现了能量为０．２１６，０．２７８，０．４３８，０．４７９ＭｅＶ的低能衰变质子．另外，还观察到了一个新的β＋延发衰变能级 Ｅｘ＝ ８．９１６ＭｅＶ，并给出了它们的相对强度．

~(230)Acβ延发裂变的观测(英文)

搜索了２３０Ａｃβ延发裂变．由 ６０ＭｅＶ／ｕ１８Ｏ离子照射２３２Ｔｈ，通过多核子转移反应产生２３０Ｒａ．经放射化学分离和薄的２３０Ｒａ→β－２３０Ａｃ源的制备，获得了 １０８ 个２３０Ａｃ原子．该源对云母裂变径迹探测器曝光．借助于所测的γ能谱和两个裂变事件，鉴别了β延发裂变核２３０Ａｃ，得到了它的β延发裂变几率为（１． １９± ０．８５）× １０－８．

Studies on the exotic structure of Al-23

The longitudinal momentum distribution (P-//) of fragments after one-proton removal from Al-23 and reaction cross sections (sigma(R)) for Al-23,Al-24 on carbon target at 74A MeV have been measured simultaneously. An enhancement in sigma(R) is observed for Al-23 compaxed with Al-24. The full width at half maximum of the P-// distribution for Mg-22 fragments has been determined to be 232 +/- 28 MeV/c. Analysis of P-// using the Few-Body Glauber Model indicates a dominant d-wave configuration for the valence proton in the ground state of Al-23. The exotic structure in Al-23 is discussed.

Production cross-section of Ra-230 in the reaction of 60 MeV/u O-18 ions with U-238

A thick natural uranium target was bombarded with a 60 MeV/u O-18 beam. The neutron-rich isotope Ra-230 as the target residue was produced through the multinucleon transfer reaction (U-238-4p-4n). The barium and radium fraction as BaCl2 precipitate were radiochemically separated first from the mixture of uranium and reaction products. Then, the radium fraction was separated from BaCl2 precipitate by using cation exchange technique. The gamma-ray spectra of the Ra fraction were measured using an HPGe detector. The production cross sections of Ra-230 were obtained by a combination of the radiochemical separation technique and off-line gamma-ray spectroscopy. The cross section of Ra-230 has been determined to be 66 +/- 20 mu b.

Effects of annealing on the photoluminescence of He ion implanted sapphire after 230-MeV Pb ion irradiation

Single crystal sapphire (Al2O3) samples implanted with 110 keV He and irradiated at 320 K by Pb-208(27), ions with energy of 1.1 MeV/u to the fluences ranging from 1 X 10(12) to 5 X 10(14) ion/cm(2) and subsequently annealed at 600, 900 and 1100 K. The obtained PL spectra showed that emission peaks centred at 375, 390, 413, and 450 nm appeared in irradiated samples. The peak of 390 ran became very intense after 600 K annealing. The peak of 390 nm weakened and 510 nm peak started to build up at 900 K annealing, the peak of 390 nm vanished and 510 nm peak increased with the annealing temperature rising to 1100 K. Infrared spectra showed a broadening of the absorption band between 460 cm(-1), and 510 cm(-1) indicating strongly damaged regions being formed in the Al2O3 samples and position shift of the absorption band at 1000-1300 cm(-1) towards higher wavenumber after Pb irradiation.

Photoluminescence of inert-gas ion implanted sapphire after 230-MeV Pb ion irradiation

In the present work the photoluminescence (PL) character of sapphire implanted with 110-keV He, Ar or Ne ions and subsequently irradiated with 230-MeV Pb was studied. The implantation was performed at 320 and 600 K using fluences from 5.0 x 10(16) to 2.0 x 10(17) ions/cm(2). The Pb ion irradiation was carried out at 320 K. The obtained PL spectra showed peaks at 375, 413 and 450 nm with maximum intensity at an implantation fluence of 5.0 x 10(16) ions/cm(2) and a new peak at 390 nm appeared in the He-implanted and subsequently Pb-irradiated samples. Infrared spectra showed a broadening of the absorption band between 460 and 510 nm indicating strongly damaged regions formed in the Al2O3 samples. A possible PL mechanism is discussed.

MEASUREMENT OF TWO-PROTON CORRELATION FROM THE BREAK-UP OF Al-23

Experiments of Al-23 and Mg-22 radioactive beams bombarding a C-12 target at an energy of 60 similar to 70 A MeV have been performed at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility to study the two-proton emission from Al-23 and Mg-22 excited states, respectively. The trajectorie of the decay products, namely Na-21 + p + p from Al-23 and Ne-20 + p + p from Mg-22, are clean identified. The relative momentum and opening angle between two protons in the rest frame of three body decay channels are obtained by relativistic-kinematics reconstruction. The results demonstrate that there are some di-proton emission components from He-2 cluster for the excited Al-23 and Mg-22.