用VHDL实现的23位快速浮点数加减法器

With the development of LSI, FPGA/CPLD has been used more and more in the fields of digital signal processing and au-tocontrol and so on. And with the development of the techniques of digital processing, for fitting the system’s function, it should be a higher requirement to speed and used-resource to compute the floating point numbers. The author introduces a high speed adder-subtracter of the 23 bit’s floating point numbers, which is carried out with the parallel arithmetic and the computational speed cou...中文文摘：随着大规模集成电路的不断发展,FPGA/CPLD在数字信号处理、自动控制等方面得到了越来越多的应用。并且伴随着数字化处理技术的不断发展,为满足系统功能的要求,对浮点数运算的速度以及相应占用的资源也就提出了更高的要求。笔者即介绍了以VHDL语言为基础,采用并行算法且计算速度达到33MHz的,对23位标准浮点数实现的高速浮点加减法运算器,并以Cyclone II芯片EP2C20F484为硬件环境,最终进行时序模拟仿真,从而验证该浮点加减法器的正确性和快速特性。

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

~(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．

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.

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.