Heavy ion timing with channel-plates

Girard, J.; Bolore, M.

doi:10.1016/0029-554x(77)90295-6

Cited by 52 publications

(7 citation statements)

References 1 publication

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“…After partial differentiation of this relation and substi- (12) from which it is clear that a much smaller energy spread is needed than in our case. The spread in the flight length I has to be smaller than 0.5%.…”

Section: B Experimental Range and Resolutionmentioning

confidence: 59%

Time and position-sensitive detector for dissociative processes in fast beams

Bruijn

Los

1982

Review of Scientific Instruments

181

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A microchannel-plate detector has been developed to detect the time and position of two particles simultaneously. High resolution in position and timing is achieved with 100 J.l-m FWHM and 0.5 ns FWHM, respectively. The detector is designed to measure dissociative processes of molecules in fast beams. The released kinetic energy and the direction of the associated momentum with respect to the beam direction in the center of mass can be determined directly. This method offers big advantages over the determination by means of a mass spectrometer which is common practice in the field of "translational spectroscopy." The efficiency is increased by a factor of 10 3 _10 5 with comparable energy resolution. Measurements are performed on the dissociative charge exchange of Hi with Mg atoms. In the range of 7.2-10.2 eV 17 discrete energies are observed due to the predissociation of the c 3 1Tu state in H2 and presumably also the c 11Tu state.

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Section: B Experimental Range and Resolutionmentioning

confidence: 59%

Time and position-sensitive detector for dissociative processes in fast beams

Bruijn

Los

1982

Review of Scientific Instruments

181

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“…The same potential was applied to the front of the MCr as was to the final grid and an insulated drift tube within the vacuum system. We have constructed for the MCr a conical anode of approximately 50-H impedance [10][11][12] to match the 50-H input of a LeCroy (Chestnut Ridge, NY) 9450 digital oscilloscope with a bandwidth limit of 350 MHz. The oscilloscope was capable of sum-averaging up to 10 6 traces with a time resolution of 2.5 ns in the normal mode or to 0.1 ns in the random-interleave sampling mode (RIS).…”

Section: Methodsmentioning

confidence: 99%

Resolution limitations from detector pulse width and jitter in a linear orthogonal-acceleration time-of-flight mass spectrometer

Coles

Guilhaus

1994

J. Am. Soc. Mass Spectrom.

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Recent and ongoing advances in timing electronics together with the development of ionization techniques suited to time-of-flight mass spectrometry (TOF-MS) have contributed to renewed interest in this method of mass analysis. Whereas low resolving powers (m/†m < 500) were once an almost unavoidable drawback in TOF-MS, recent developments in instrument geometries have produced much higher resolving powers for many ion sources. The temporal width of detector pulses and jitter in timing electronics, however, lead to contributions to peak widths that are essentially independent of the mass-analyzer ion optics. The effective detector pulse width (†t d ≈ 1-10 ns typically) can be a limiting factor in the development of high resolution time-of-flight (TOF) instruments with modest drift lengths (∼1 m), It also reduces the mass resolution more seriously for light ions. This article presents a method for distinguishing the instrumental "ion arrival-time" resolution (R o) of a linear TOF mass analyzer from that which is locally measured at a particular mass, limited by the broadening of the detector pulse width and electronics. The method also provides an estimate of †t d, that is useful in determining the temporal performance of the detection system. The model developed here is tested with data from a recently constructed orthogonal-acceleration TOF mass spectrometer equipped with a commercially available transient recorder (a LeCroy 400-Msamplejs digital oscilloscope) from which we obtained R o = 4240 ± 100 [full width at half maximum (FWHM)) and †t d = 3.0 ± 0.1 ns (FWHM).

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“…The start detector consisted in a thin C foil associated with channel plates [13][14]. In order to increase the number of extracted electrons, magnesium oxide was deposited on the carbon foil.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Peripheral Ar induced reactions at 44 MeV/u — similarities and deviations with respect to a high energy fragmentation process

et al. 1983

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Peripheral Ar reactions induced at GANIL at 44MeV/u have been analyzed in the framework of the high energy fragmentation model. Several deviations from this model have been interpreted as due to the persistence of some collective effects at this intermediate energy.Heavy ion induced reactions in the energy region between 20 and 100MeV/u appear to be very interesting as one expects a strong evolution in the reaction mechanism. A transition from the low energy one body dissipation process to two body friction should show up. As far as peripheral reactions are concerned it has been shown that at 20MeV/u with "light" heavy projectiles (M<20) the momentum widths of the ejectile were too narrow [1, 3] to be described by the standard high energy fragmentation models [4][5][6]. On the other hand, in the energy range 60-120 MeV/u there is a better agreement, the remaining difference with high energy data [7-10] arising from Final State Interactions (FSI). The latter have been described in terms of the combined Coulomb and nuclear field between the ejectile and the remaining target like nucleus or/and the Coulomb field between the ejectile and the cloud of removed protons and other light charged particles [-10]. The FSI are revealed by a broadening of the transverse momentum distributions, as compared to the longitudinal ones [7][8]. In order to further investigate these questions we have initiated Ar induced reactions at 44MeV/u, i.e. in an energy domain not explored so far with this relatively massive type of projectile. The fragmentation (or fragmentation-like data) will be compared to what has been observed at high energy by Viyogiet al. [11]. The advantage of Ar over lighter projectiles lies in the fact that struc-* This experiment has been performed at the GANIL national facility at CAEN ture effects in the projectile are less important. Furthermore the large diversity of ejectile (twelve elements with six or seven isotopes each were recorded in the present experiment [12]) makes easier to follow the evolution from the most peripheral collisions to some more inner ones. The data related to the mass and charge distributions of the fragments have been presented elsewhere [-12]. It was concluded that at this intermediate energy and for this particular aspect the dominant process was fragmentation. The present paper is mainly devoted to the energy and angular distributions of the fragments. The deviations from a fragmentation picture will be emphasized. At 44MeV/u bombarding energy such a simple model assuming a clean cut between participants and spectators does not seem to be adequate to reproduce all the observed features. It will be shown that quasi elastic exchanges of nucleons take place on the one hand and that dissipative phenomena manifest themselves clearly on the other hand. The paper will be arranged in the following way. In the first chapter a description of the experimental set up will be given, then, in a second part a general survey of the data will be made. Finally, analyzing the data in terms of a fragme...

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Heavy ion timing with channel-plates

Cited by 52 publications

References 1 publication

Time and position-sensitive detector for dissociative processes in fast beams

Time and position-sensitive detector for dissociative processes in fast beams

Resolution limitations from detector pulse width and jitter in a linear orthogonal-acceleration time-of-flight mass spectrometer

Peripheral Ar induced reactions at 44 MeV/u — similarities and deviations with respect to a high energy fragmentation process

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