Velocity measurements of recoil nuclei from α-decay and the determination of their mass

doi:10.1016/0029-554X(72)90774-4

Nuclear Instruments and Methods

Volume 99, Issue 2, 1 March 1972, Pages 179-182

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Abstract

Using a time of flight method the velocity of nuclei recoiling from α-decay has been measured. The recoils are detected by NE102A plastic scintillator. The use of this technique to measure the mass of α-emitting isotopes is described.

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Cited by (4)

Evidence for long-lived isomeric states in neutron-deficient 236Am and 236Bk nuclei
1987, Physics Letters B
A time-of-flight mass spectrometer for recoil particles from α-active sources produced by a He-jet
1978, Nuclear Instruments and Methods
A time-of-flight mass spectrometer has been developed for α-active sources prepared continuously by the He-jet of the UNILAC. For a high transport yield the He-jet was loaded with aerosol particles which were evaporated from the target foil by heating. The method was applied to on-line produced nuclei from the reaction ⁸⁴Kr+^natGe using a channel plate as stop-detector and from ⁸⁴Kr+¹⁰³Rh using a scintillation counter. The system with the scintillation counter turned out to have a detection efficiency of 0.5% at an α-energy resolution of 30 keV. First on-line experiments were intended to detect new Tl-isotopes, however only several known Pt- and Au-isotopes were observed, indicating that the used He-jet system did not accumulate thallium.
Lifetime measurements of excited states in 219Rn by observation of conversion-electron doppler shifts following α-decay
1974, Nuclear Instruments and Methods
A method is described in which the observation of conversion- electron Doppler shifts is used to measure nuclear lifetimes in the picosecond range. The isometric nuclei recoil into the vacuum chamber of an orange-type β-spectrometer following α-emission. The recoil velocity is measured directly by a time-of-flight technique. For the lifetime measurements the recoil distance is limited by a stopper foil, the position of which is varied in a reproducible way using the thermal expansion of a metal holder rod. Since the distances are in the micrometer region, an optical interference method can be applied to measure directly the variation in distance. The fraction of conversion electrons in the unshifted conversion line represents the fraction of isomeric nuclei which do not decay in flight. The nuclear lifetime is derived directly from the variation of this quantity with the recoil distance.
This method should be applicable to many excited states of nuclei in the Z > 82 region, where common techniques fail. Lifetimes are accessible in the range $1 ps <T_{12} <100 ps$ .
An application to three excited states in ²¹⁹Rn gave the following results:
- •
 $T_{12} (159 keV) = (17.7±2.6) × 10^{−12} s$ ,
- •
 $T_{12} (269 keV) = ( 4.4±1.0) × 10^{−12} s$ ,
- •
 and $T_{12} (339 keV) = ( 8.1±2.8) × 10^{−12} s$ .
Development of organic scintillators
1979, Nuclear Instruments and Methods
The development of organic scintillators is reviewed with emphasis on work that has been reported since 1964. The scintillation process is discussed. Measurements of scintillator properties such as response-energy dependence, energy resolution, timing characteristics, pulse shape discrimination and scintillation anisotropy are reviewed. Some recent and novel applications of organic scintillators are noted.

^∗: On leave from Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.

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Nuclear Instruments and Methods

Abstract

References (9)

Phys. Rev. Letters

Z. Physik

Bull. Res. Council Israel

Phys. Rev.

Mat. Fys. Medd. Dan. Vid. Selsk.

Cited by (4)

Evidence for long-lived isomeric states in neutron-deficient <sup>236</sup>Am and <sup>236</sup>Bk nuclei

A time-of-flight mass spectrometer for recoil particles from α-active sources produced by a He-jet

Lifetime measurements of excited states in <sup>219</sup>Rn by observation of conversion-electron doppler shifts following α-decay

Development of organic scintillators