Development of an in-air RBS technique using a metal capillary

We have developed a simple Rutherford backscattering spectroscopic (RBS) method to analyze sample depth profiles in air. To avoid excessive energy loss of projectile ions in air, we have used a 3 MeV proton beam extracted into air with a metal capillary. Using this capillary, we were able to extract a sufficiently large proton beam current to perform in-air RBS and in-air PIXE without requiring any window, such as a thin film, between a vacuum chamber and air. We have validated our technique by analyzing the depth profiles for Au foils of various thicknesses, 0.25, 0.75, and 2.5 μm. A comparison of the experimental results with a simple theoretical calculation indicates that this technique is useful for analyzing the depth profile of any specimen in air.     

Analysis of counter ions of cyanine dye in Langmuir–Blodgett films by PIXE

Langmuir–Blodgett (LB) films of 1-methyl-1^′-octadecylquinocyanine bromide, iodide and perchlorate were prepared from subphases containing NaClO₄, KBr and/or KI. Each sample consists of an arachidic cadmium layer and about 100 cyanine dye layers on a Si substrate. Anions incorporated into the film as counter ions from the subphase were analyzed by particle induced X-ray emission (PIXE) using a 2.5 MeV He²⁺ beam. It was found that the dissociation of the cationic dye molecule in the monolayer at the air/water interface leads to the substitution of counter anions of the dye molecules, and the subsequent incorporation of the counter anions in the LB films. Some of the dissociation constants of cyanine halide dyes were estimated.     

Elemental analysis of edible grains by micro-PIXE: Common buckwheat case study

The aim of this study was the adaptation of the micro-PIXE method for analysis of nutritionally relevant heavy elements in different tissues of the grain of common buckwheat (Fagopyrum esculentum), as a representative nutritionally interesting grain food source. At 57% of the buckwheat grain biomass, the endosperm was a modest nutrient source when compared to the cotyledons, at 17% of the biomass. These latter contained high concentrations of trace elements, representing 91% of the total grain Zn, 87% for P, 70% for S, 62% for Mg, 60% for K, 54% for Cu, 53% for Mn and 35% for Fe. The husk provided storage for 85% of the total Ca, 84% for Al, 83% for Si, 76% for Cl, 69% for Ti and 46% for Fe. Knowledge on these preferential elemental constitutions of the different grain tissues makes the possibility of designing target products with nutritionally optimal constitution more feasible. These data represent a basis for a more targeted approach to nutritional improvement of grains intended for human consumption.     

重离子束治癌装置及技术发展

首先简要回顾了重离子束治癌在我国的兴起与发展的情况.随后着重介绍了重离子束治癌装置及部分关键技术:总体布局方案、束流引出模式、束流配送系统、束流旋转机架、辐照门控系统、PET成像等.     

Measurement of 79Se by accelerator mass spectrometry using projectile X-ray technique

1IntroductionInacceleratormassspectrometry(AMS)measurementsoflong-livedradioisotopes,stableisobarsarethedominantbackground.FortheradioisotopesofatomicnumberZ520,theisobarsbackgroundcanbeeliminatedbymeansofthedifferentenergylossofisobarinmatterduetotherateofenergylossisafunctionofZ.Butwithincreasingatomicnumber,theenergystragglingincreasesrelativetotheenergylossdifference,sothatisobarseparationbecomesprogressivelylesseffective.Inordertoseparatetheisobarswithhigheratomicnumberstheionenergyhast…     

Development of MRPC technology for STAR-TOF

A prototype of multi-gap resistive plate chamber （MRPC） modules with 6 gas gaps of 220 μtm used for the time-of-flight （TOF） detectors has been developed by STAR TOF group. A tray （TOFr） composed of 28 MRPC modules was constructed and operated in STAR for the d＋Au collisions and Au＋Au collisions during 2003 RHIC and 2004 RHIC run. Results show its time resolution is 85 ps with the average efficiency of 95% and clear identification of K/π up to 1.6 GeV and proton/K up to 3.0 GeV.     

用计算机模式识别法和PIXE法研究人发中元素在食管癌诊断中的作用

用ＰＩＸＥ方法对华北地区的４１４例食管癌、食管上皮重度增生病人和正常人的头发样品中的１２种元素进行了测定。经过ｔ检验发现，癌症病人与正常人比较，１０种元素（Ｓｉ，Ｓ，Ｃａ，Ｃｒ，Ｍｎ，Ｆｅ，Ｎｉ，Ｃｕ，Ｐｂ，Ｓｒ）有显著差异；食管上皮重度增生病人和正常人比较，９种元素（Ｓｉ，Ｐ，Ｓ，Ｃａ，Ｃｒ，Ｍｎ，Ｆｅ，Ｎｉ，Ｚｎ）有显著差异，说明头发中微量元素的变化先于人体内食管的癌变。用计算机模式识别法对上     

Analysis of atmospheric aerosols by particle-induced X-ray emission, instrumental neutron activation analysis, and ion chromatography

Particle-induced X-ray emission (PIXE), ion chromatography (IC), and occasionally also instrumental neutron activation analysis (INAA) were used in combination for the analysis of atmospheric aerosol samples that were collected on Nuclepore polycarbonate filters. A comparison of the results enabled us to evaluate the matrix effects (i.e., particle size effects) of the PIXE analysis for the light elements and to assess the water-solubility and/or speciation of a number of elements (e.g., S, K, Ca). Results are presented from several measurement campaigns at urban and forested sites in Europe, whereby PM10 or PM2.5 filter samples were taken. From the PIXE and IC results for a 2003 summer campaign at the K-puszta site in Hungary, it was estimated that organosulphates could be responsible for 20% of the total sulphur concentration and 30% of the organic aerosol in PM10. The comparison of the IC and PIXE data for K and Ca from the various sites indicated that most of the Ca was water-soluble (the mineral dust Ca was presumably mostly present as calcite, and perhaps also in part as gypsum); in contrast, for K, only half of it was typically water-soluble, indicating that it was to a large extent associated with insoluble mineral dust. Exceptions, with almost fully water-soluble K, were found for samples that were substantially impacted by biomass burning.     

Characterisation of ferromagnetic magnetic storage media surfaces by complementary particle induced X-ray analysis and time of flight-energy dispersive elastic recoil detection analysis

Thin (10 nm–1 μm) films of ferromagnetic material constitute an important class of materials that are difficult to analyse by conventional ion beam analytical (IBA) techniques because they are based on the ferromagnetic elements (Co, Fe, Mn, Ni, and Cr). The similar or overlapping isotope masses makes it difficult to separate the elemental signals using time of flight and energy dispersive elastic recoil detection (ToF-E ERD). In this exploratory study we have investigated the use of Particle Induced X-ray Emission (PIXE) measurements to refine the mass dispersive depth profile information from ToF-E ERD. The surfaces of two commercial magnetic media were investigated. One sample was a double density diskette with a coating of ferrite particles in an organic binder. The other sample was a complex C/Co/Cr/Ni–P/Al multilayer structure taken from a standard hard disc. The Lund nuclear microprobe with a 2.55 MeV proton beam was used for PIXE analysis. ToF-ERD measurements were carried out using a 55 MeV ¹²⁷I¹⁰⁺ ion beam incident at 67.5° to the surface normal. The time of flight and kinetic energy of recoils ejected at 45° to the ion beam direction was measured in a detector telescope. The findings demonstrate that by detailed analysis of the PIXE spectra it is possible to remove the ambiguities in mass assignment of the ToF-ERD data associated with the ferromagnetic elements.