The 3He long-counter TETRA at the ALTO ISOL facility

Commissioning of the BRIKEN detector for the measurement of very exotic β-delayed neutron emitters

“…Combining quadratically the statistical and systematic uncertainties our result is P 1n = 19.10(80)%. It agrees within uncertainties with the weighted average of previous measurements with the lower P 1n values [36,37,32] , P 1n = 20.4(12)%. The result confirms also the value of the nominal efficiency used.…”

“…During the commissioning run we accumulated 3.5×10 5 ions of 82 Ga, a good case to verify the neutron efficiency since the P 1n for this decay is fairly well known. There are three previous measurements which give consistent values: 21.4(22)% [36], 19.8(10)% [37], and 22.2(20)% [32]. Their weighted average gives 20.4(12)%.…”

“…One possibility is to use the intensity of decay γ-rays observed in the CLOVER detectors to obtain information on the average β efficiency. This requires the comparison of β-gated with ungated γ ray spectra [32], but it is in practice difficult to apply because of the large background and the limited statistics. Another approach is to calculate a realistic β efficiency curve from Monte Carlo simulated data and use β intensity distributions to compute the average efficiencies (Section 3).…”

Characterization of a cylindrical plastic β-detector with Monte Carlo simulations of optical photons

“…This method of rejecting the background has been applied mainly with silicon detectors and plastic scintillator detectors. It is important to maximize the β-detection efficiency in order to maximize the statistics and lower the detection limit, as has been shown in different experimental set-ups with germanium detectors [1,2] or neutron counters [3]. In the particular case of a Total Absorption γ-ray Spectroscopy (TAGS) experiment, as well as in experiments with neutron detector arrays, large 4π detectors are used in order to maximize the efficiency.…”

“…A simple and convenient way to maximize the β-detection efficiency, minimizing at the same time the γ sensitivity, is to build a hollow cylinder of thin plastic scintillation material surrounding the source [1,2,3]. Closing one end of the cylinder with scintillation material is a practical way to allow the attachment of a photomultiplier tube (PMT) for light readout, while leaving the other end free for transporting the radioactivity inside the detector, as will be shown in Fig.…”