May 12, 2016

4)X-ray Spectrometry– HVC Capacitor, HV Ceramic Capacitor to build All kinds of X-ray machine.

4)X-ray Spectrometry–  HVC Capacitor, HV Ceramic Capacitor to build All kinds of X-ray machine.

The energy resolution of the gaseous ED detectors is more
and more comparable to that of the semiconductor detectors; in
addition, the structure of this low-cost detector is not complex
and constructing it is much easier than for high-purity Ge or Si(Li)
detectors. Beyond that they can have large area window for the
entering X-rays and they have less sophisticated operating
requirements than solid-state detectors, up to 25-keV X-ray energy.
A Portuguese research group ( B18) improved their xenon-filled
gas proportional-scintillation counter, applying a polyimide window
with 6-mm diameter with30% transmission at 250 eV for soft
X-ray energies below 3 keV. The pressure was set as 800 Torr,
and the gas was continuously purified by convection, using
nonevaporable getters allowing the same operating gas during
several months. The gaseous detector is also one of the most
suitable devices for two-dimensional X-ray imaging because this
type of detector can be constructed with a large sensitive area.
A European research group at ELETTRA (B19 ) reviewed a
two-dimensional X-ray imaging detector based on a single-photon
counter that has a gas electron multiplier (GEM) inner structure.
The GEM detector was applied for detecting X-rays having energy
of 8 keV, and it was capable of time-resolving spectral data down
to millisecond time. The sensitive area of the detector was 56 
56 mm, divided into sevenxy cells; the voltage of the drift cathode
was set at 4000 V. On the basis of the electronic signals, each
cells of the GEM can be subdivided into virtual pixels (ViP) having
a sensitive spatial resolution of 100 ím (fwhm). This detection
property depends significantly on the speed of the applied
electronics and the gas gain, which was 10
. The authors
concluded on the basis of their experience that the ViP detector
offers a high quantum efficiency up to 25-keV X-ray energy using
2  10
Pa pressure of Xe mixture gas, and the time resolution,
which determines the special resolution, can be improved down
to a few hundred nanoseconds. A special application of large-area
gaseous detector was shown by the research group of Despre´s
(B20 ) by construction of a new radiographic scanning system.
The detector was built by two orthogonally oriented gas microstrip
detectors used for scanning a human body with a speed of 15
cm/s. Both detectors consisted of 1764 channels, and the
individual pixel sizes in the obtained X-ray image were 0.254 
0.254 mm
. Due to the favorable detection properties, such as short
signal evaluation and large sensitive area, this newly constructed
device is a future candidate for low-dose radiography, since the
entrance dose rate at the irradiated human skins was 0.1 mSv
while at the case of conventional X-ray films this value is close to
1.45 mSv.

A review article was published by Shekhtman ( B21 ) describing
the newest design of micropattern detectors and gap-resistive plate
chambers and the general operating effects and processes, the

design structure, and their influence on the properties of the
gaseous detectors. The efficiency through the absorption strongly
correlated with the atomic number of the gas material (Ar, Kr,
Xe) and its pressure. The article overviewed the most important
application areas of the gaseous detectors: (i) wire chambers for
medical radiography applications and for SR, and (ii) micropattern
gas detectors and gas electron multiplier-based detectors for high
count rate synchrotron experiments.
Newbury (B22 ) tested and applied a silicon multicathode drift
detector for X-ray spectrometry on a SEM investigating spectros-
copy parameters such as the output count rate, energy resolution,
and peak stability in the ED spectra. He demonstrated the
capability of this multichannel SDD for recording an X-ray
spectrum image of an Al -Ni alloy containing 4 wt % Fe as well in
a 128  128 pixel size with 220-kHz output rate. The X-ray
spectrum image was generated by fixing the excitation electron
beam, and the SDD array was readout, and in this way the overall
mapping time was found to be 185 s while 100 Mb information
was produced. Comparing with a Si(Li) detector having a 50 mm
area, he found that the array SDD has a better resolution, namely,
134 eV fwhm at 6.4 keV (the resolution of Si(Li) was 140 -145
eV), and the SDD can achieve a shorter peaking time for a given
The main advantages of the silicon drift detectors (SDD) are
the high count rate capability, the possibility of a large effective
detection area, and the relatively high working temperature (-10
°C to room temperature). The main idea is that the signal charges
generated in the bulk crystal are transported to the electrodes in
a controlled way, mainly parallel to the large surface of the
detector. Gatti and Rehak (B23 ) reviewed the principal properties
of the SDD, discussed different applications in charged particle
physics and XRS, and gave a short description about their physical
structure and the physical processes in the detector bulk, e.g.,
Fe spectra recorded with a ring-shaped SDD at -10°C, in
which spectra the two Mn lines were clearly resolved.
The working capabilities of two standard Si PIN and conven-
tional Si(Li) detectors were studied by Kump and co-workers
(B24 ) using
Fe and
Cd annular radioactive sources and the
same measuring geometrical configuration set up. The 0.3-mm-
thick PIN diode had a 7-mm
active area, and the energy resolution
at count rates 1000 counts/s was found to be 195 eV, while the
parameters for the Si(Li) detector were 30 mm
, and fwhm of 175
eV (and this value is worse than the average energy resolution of
commercial Si(Li) detectors). The authors compared the analytical
capabilities of these detectors by quantitative analysis of SRM 2710
soil standard sample, a similar dependence of sensitivities versus
atomic number was found up to Z ) 30, and over this value, much
less sensitivity was obtained with the PIN diode due to the lower
detection efficiency.
A new set of large area HPGe detector was reviewed in ref
B25 for the purpose of PIXE analysis. The detector set is built in
annular form of eight individual detectors, and each item had a
effective area; this provides high quantum efficiency. The
detector chambers are mounted vertically, and each subdetector
acts as an individual detector; however, they use a common main
amplifier. The fwhm of the set of detectors was found to be
between 144 and 168. The authors outlined the unique spectro-
scopic properties of this set, which can be used for detection of

very low X-ray fluxes, and the subdetectors can separately be
tuned with the use of suitable absorption filter in front of them
for different X-ray energies.

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