How many tubes have been used in different measurements?

The current version has fortyeight 3He tubes, but previous versions with twenty [13, 14] and thirty [15] tubes have been used in different measurements.

What is the only free parameter in the fit?

Therefore the only free parameter in the fit is the product of the number of implanted parent ions430 (timpl × R1 or ∑ k N1(tk)) times the detection efficiency.

How was the ratio of to neutron detection efficiencies determined?

The ratio of β to neutron detection efficiencies for this setup, which710 is the parameter used for the determination of Pn values, was determined with an uncertainty of 1.6%.

How long is the time for neutrons to moderate their energy in the polyethylene?

The time for neutrons to moderate their energy in the215polyethylene and be captured in 3He is quite long, up to several hundreds of microseconds (see Fig. 6 and Section 4).

How many cycles can be well represented by a constant value?

The authors calculated the time dependence of the accumulated activity, not removed by the tape system, and425 concluded that after several measuring cycles it can be well represented by a constant value.

How is the calibration of the spectrum made?

The calibration of the β spectrum is made by comparison with Monte Carlo simulations of the energy deposited in the Si detector (see Section 5).

Open AccessJournal Article10.1016/J.NIMA.2015.10.082

Characterization of a neutron–beta counting system with beta-delayed neutron emitters

J. Agramunt, +35 more

- 21 Jan 2016

- Nuclear Instruments & Methods in Physics...

- Vol. 807, pp 69-78

TL;DR: In this paper, a new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known β delayed neutron emission properties, and a new accurate value of the neutron emission probability for the important delayed-neutron precursor 137I was obtained, P n = 7.76 (14 ) %.

Abstract: A new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known β-delayed neutron emission properties. The setup consists of BELEN-20, a 4π neutron counter with twenty 3He proportional tubes arranged inside a large polyethylene neutron moderator, a thin Si detector for β counting and a self-triggering digital data acquisition system. The use of delayed-neutron precursors with different neutron emission windows allowed the study of the effect of energy dependency on neutron, β and β–neutron rates. The observed effect is well reproduced by Monte Carlo simulations. The impact of this dependency on the accuracy of neutron emission probabilities is discussed. A new accurate value of the neutron emission probability for the important delayed-neutron precursor 137I was obtained, P n = 7.76 ( 14 ) %.

1. What have the authors contributed in "Characterization of a neutron-beta counting system with beta-delayed neutron emitters" ?

The use of delayed-neutron precursors with different neutron emission windows allowed the study of the effect of energy dependency on neutron, β and β-neutron rates.

2. What is the effect of the inevitable noise discrimination threshold in the counter?

The inevitable noise discrimination threshold in the β counter leads to a strong efficiency variation with end-point energy in the upper part of730 the decay window.

3. How many slabs are used to make the neutron moderator?

The neutron shielding on the190 sides of the moderator block has a thickness of 200 mm and is assembled from twelve different PE slabs.

4. What type of detectors have been used to characterize the neutron-beta counting?

The DACQ has been also applied to other types of detectors like liquid scintillation detectors for neutron detection [32] and a NaI(Tl) total absorption330 γ-ray spectrometer [33].

Characterization of a neutron–beta counting system with beta-delayed neutron emitters

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Most frequently asked questions

1. What have the authors contributed in "Characterization of a neutron-beta counting system with beta-delayed neutron emitters" ?

2. What is the effect of the inevitable noise discrimination threshold in the counter?

3. How many slabs are used to make the neutron moderator?

4. What type of detectors have been used to characterize the neutron-beta counting?

5. How many tubes have been used in different measurements?

6. What is the only free parameter in the fit?

7. How was the ratio of to neutron detection efficiencies determined?

8. How long is the time for neutrons to moderate their energy in the polyethylene?

9. How many cycles can be well represented by a constant value?

10. How is the calibration of the spectrum made?

Figures

Citations

Conceptual design of the BRIKEN detector: A hybrid neutron-gamma detection system for nuclear physics at the RIB facility of RIKEN

Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated He 3 counters

Total absorption $\gamma$-ray spectroscopy of the $\beta$-delayed neutron emitters $^{137}$I and $^{95}$Rb

The ORNL analysis technique for extracting β-delayed multi-neutron branching ratios with BRIKEN

Improving fission-product decay data for reactor applications: part I—decay heat

References

Geant4—a simulation toolkit

Geant4 - A Simulation Toolkit

ROOT — An object oriented data analysis framework

The Ame2012 atomic mass evaluation

GEMS: Underwater spectrometer for long-term radioactivity measurements

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