179 research outputs found
A position- and time-sensitive photon-counting detector with delay-line read-out
We have developed image intensifier tubes with delay-anode read-out for time-
and position-sensitive photon counting. The timing precision is better than 1
ns with 1000x1000 pixels position resolution and up to one megacounts/s
processing rate. Large format detectors of 40 and 75 mm active diameter with
internal helical-wire delay-line anodes have been produced and specified. A
different type of 40 and 25 mm tubes with semi-conducting screen for image
charge read-out allow for an economic and robust tube design and for placing
the read-out anodes outside the sealed housing. Two types of external
delay-line anodes, i.e. pick-up electrodes for the image charge, have been
tested. We present tests of the detector and anode performance. Due to the low
background this technique is well suited for applications with very low light
intensity and especially if a precise time tagging for each photon is required.
As an example we present the application of scintillator read-out in
time-of-flight (TOF) neutron radiography. Further applications so far are
Fluorescence Life-time Microscopy (FLIM) and AstronomyComment: Proceedings of SPIE Conference "Optics and Optoelectronics", 16 - 19.
Apr.200
Position-sensitive ion detection in precision Penning trap mass spectrometry
A commercial, position-sensitive ion detector was used for the first time for
the time-of-flight ion-cyclotron resonance detection technique in Penning trap
mass spectrometry. In this work, the characteristics of the detector and its
implementation in a Penning trap mass spectrometer will be presented. In
addition, simulations and experimental studies concerning the observation of
ions ejected from a Penning trap are described. This will allow for a precise
monitoring of the state of ion motion in the trap.Comment: 20 pages, 13 figure
Transfer ionization and its sensitivity to the ground-state wave function
We present kinematically complete theoretical calculations and experiments
for transfer ionization in HHe collisions at 630 keV/u. Experiment and
theory are compared on the most detailed level of fully differential cross
sections in the momentum space. This allows us to unambiguously identify
contributions from the shake-off and two-step-2 mechanisms of the reaction. It
is shown that the simultaneous electron transfer and ionization is highly
sensitive to the quality of a trial initial-state wave function
Time and position sensitive single photon detector for scintillator read-out
We have developed a photon counting detector system for combined neutron and
gamma radiography which can determine position, time and intensity of a
secondary photon flash created by a high-energy particle or photon within a
scintillator screen. The system is based on a micro-channel plate
photomultiplier concept utilizing image charge coupling to a position- and
time-sensitive read-out anode placed outside the vacuum tube in air, aided by a
standard photomultiplier and very fast pulse-height analyzing electronics. Due
to the low dead time of all system components it can cope with the high
throughput demands of a proposed combined fast neutron and dual discrete energy
gamma radiography method (FNDDER). We show tests with different types of
delay-line read-out anodes and present a novel pulse-height-to-time converter
circuit with its potential to discriminate gamma energies for the projected
FNDDER devices for an automated cargo container inspection system (ACCIS).Comment: Proceedings of FNDA 201
Transition From Quantum To Quasi-classical Behaviour Of The Binary Encounter Peak In Collisions Of 0.6 To 3.6 Mev Amu“¹ I23+ And Xe21+ With He And Ar
Double differentia] cross sections are reported for the production of binary encounter electrons in collisions of 0.6 MeV amu-1 I23+ and 1.4, 2.4, and 3.6 MeV amu-1 Xe21+ projectiles incident on He and Ar targets. Electron energy spectra were measured between 0: and 45: in the case of the two lower projectile energies, and between 17.5° and 60- for the two higher projectile energies. The data are compared with quantum mechanical impulse approximation and classical trajectory Monte Carlo calculations. While the quantum model calculation predicts a rapid disappearance of diffraction effects in the binary encounter peak with increasing projectile energy, these remain visible in the experimental results up to the highest energy measured. The necessity of including multiple target ionization involving inner shell electrons in the theoretica] description of the collision process is demonstrated by the classical trajectory Monte Carlo calculation, which accounts well for the shape of the 2.4 and 3.6 MeV amu-1 cross sections, except at angles where diffraction effects are manifest. Systematic shifts of the binary encounter peak position towards lower energies with increasing emission angle were observed for all projectile energies. © 1993 IOP Publishing Ltd
Carbon K-shell Photo Ionization of CO: Molecular frame angular Distributions of normal and conjugate shakeup Satellites
We have measured the molecular frame angular distributions of photoelectrons
emitted from the Carbon K shell of fixed-in-space CO molecules for the case of
simultaneous excitation of the remaining molecular ion. Normal and conjugate
shake up states are observed. Photo electrons belonging to normal \Sigma
-satellite lines show an angular distribution resembling that observed for the
main photoline at the same electron energy. Surprisingly a similar shape is
found for conjugate shake up states with \Pi -symmetry. In our data we identify
shake rather than electron scattering (PEVE) as the mechanism producing the
conjugate lines. The angular distributions clearly show the presence of a
\Sigma -shape resonance for all of the satellite lines.Comment: 8 pages, 2 figure
Detectors for Energy-Resolved Fast Neutron Imaging
Two detectors for energy-resolved fast-neutron imaging in pulsed broad-energy
neutron beams are presented. The first one is a neutron-counting detector based
on a solid neutron converter coupled to a gaseous electron multiplier (GEM).
The second is an integrating imaging technique, based on a scintillator for
neutron conversion and an optical imaging system with fast framing capability
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