Design of the PEP-II low energy ring vacuum system

2002 ◽  
Author(s):  
D. Hunt ◽  
K. Kennedy ◽  
T. Stevens
Keyword(s):  
Low Energy ◽  
Vacuum System

α- Excited Auger Spectra

1969 ◽  
Vol 13 ◽  
pp. 418-425
Author(s):  
L. I Yin ◽  
L. Adler ◽  
R. E. Lamothe
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Auger Spectroscopy ◽  
Low Energy ◽  
Vacuum System ◽  
Light Elements ◽  
Ionization Cross ◽  
High Ionization ◽  
Auger Spectra

The possibility of obtaining Auger spectra excited by a Po 210 α-source has been investigated. The obvious advantages in the use of radioactive α-sources are simplicity, stability, and high ionization cross section for light elements. Typical spectra obtained with this method, as well as parameters affecting the characteristics of these spectra, are presented and discussed The following observations have been made: the intense low energy continuum background make it difficult to detect the presence of Auger lines in this region; the abundance of Auger lines in the above region makes identification difficult; the intensity of higher energy Auger lines is too low to be observed with the present α-source and low vacuum system; thus the practicability of α-excited Auger spectroscopy will need further investigation.

Status of the PEP-II low-energy ring vacuum system

2002 ◽  
Author(s):  
D. Cheng ◽  
D. Hunt ◽  
H. Hsieh ◽  
J. Meneghetti ◽  
K. Kennedy ◽  
...  
Keyword(s):  
Low Energy ◽  
Vacuum System

scholarly journals Operating characteristics of the low energy accelerator

2000 ◽  
Vol 18 (2) ◽  
pp. 347-352
Author(s):  
M.M. ABD EL-BAKI ◽  
M.M. ABD EL-RAHMAN
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Ion Source ◽  
Low Energy ◽  
Ion Current ◽  
Vacuum System ◽  
Pure Hydrogen ◽  
Operating Characteristics ◽  
Hydrogen Atoms ◽  
Arc Current

The main purpose of this work is to describe the construction and operation of the low energy accelerator with energy in the range from (zero to 100 KeV). This accelerator includes an ion source of the cold cathode Penning type (with pierce geometry for ion beam extraction), an accelerating tube (with 8 electrodes) and Faraday cup (FC) for measuring ion current. A vacuum system which gives vacuum of the order 3.0 × 10−8 Torr is used. A palladium tube is used to supply the source with pure hydrogen atoms. It was possible to operate this accelerator with an energy 50 KeV at minimum hydrogen pressure, 6.3 × 10−6 Torr. The total resistance applied between the accelerating electrodes RT = 31.5 MΩ. These data include the influence of the pressure in the accelerating tube, the magnetic field of the ion source, the extraction potential and the accelerating potential on the collector ion current. It was possible to accelerate protons with an energy 50 KeV with current about 100 μA at pressure 6.3 × 10−6 Torr, the source magnetic field = 110 G (IB = 2 A), the arc current = 0.4 A and the extraction potential = 10 KV.

Replication of Wet Objects and Cells

1974 ◽  
Vol 32 ◽  
pp. 102-103
Author(s):  
S. Basu ◽  
D. F. Parsons
Keyword(s):  
Water Vapor Pressure ◽  
High Vacuum ◽  
Polystyrene Latex ◽  
Vacuum System ◽  
Saturated Water Vapor ◽  
Replication Method ◽  
New Methods ◽  
Saturated Water ◽  
Water Vapors ◽  
Intermediate Chamber

We are approaching the invasiveness of cancer cells from the studies of their wet surface morphology which should distinguish them from their normal counterparts. In this report attempts have been made to provide physical basis and background work to a wet replication method with a differentially pumped hydration chamber (Fig. 1) (1,2), to apply this knowledge for obtaining replica of some specimens of known features (e.g. polystyrene latex) and finally to realize more specific problems and to improvize new methods and instrumentation for their rectification. In principle, the evaporant molecules penetrate through a pair of apertures (250, 350μ), through water vapors and is, then, deposited on the specimen. An intermediate chamber between the apertures is pumped independently of the high vacuum system. The size of the apertures is sufficiently small so that full saturated water vapor pressure is maintained near the specimen.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 314-315
Author(s):  
Earl R. Walter ◽  
Glen H. Bryant
Keyword(s):  
Sample Preparation ◽  
High Vacuum ◽  
Vacuum System ◽  
Latex Particles ◽  
New Methods ◽  
Diffusion Pump ◽  
Film Forming ◽  
Routine Basis ◽  
Distribution Studies ◽  
Preparation Techniques

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.

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