Efficiency calibration measurement and GEANT simulation of the DRAGON BGO gamma ray array at TRIUMF.

Gigliotti, D.

doi:10.24124/2005/bpgub353

Cited by 4 publications

(12 citation statements)

References 33 publications

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“…For a fixed beam energy of 27.17 MeV, we generate a simulated BGO z-position spectrum over the range of resonance energies contained within the gas target. For the simulations, we use the standard DRAGON GEANT3 package [27] and convolute the resulting BGO energies with a realistic hardware threshold. The hardware threshold was determined experimentally by taking long background runs with the threshold set to the value employed in the experiment, and to a reduced value of 50 mV.…”

Section: Methodsmentioning

confidence: 99%

“…In practice, the singles technique frequently results in a lower systematic uncertainty than the coincidence method since there is no need to estimate the γ-ray detection efficiency. This efficiency typically comes with a relative uncertainty of 10% or greater, resulting from uncertainties in the GEANT3 simulation of the BGO array [27], as well as from unknown γ-ray decay schemes. However, for reliable application of the singles technique, it is crucial that the full width of the resonance be contained within the gas target, to ensure that the thick-target approximation of the resonance strength formula is valid.…”

Section: Singles Analysismentioning

confidence: 99%

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Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Christian,

Lotay,

Ruiz

et al. 2018

Preprint

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Background: Classical novae are cataclysmic nuclear explosions occurring when a white dwarf in a binary system accretes hydrogen-rich material from its companion star. Novae are partially responsible for the galactic synthesis of a variety of nuclides up to the calcium (A ∼ 40) region of the nuclear chart. Although the structure and dynamics of novae are thought to be relatively well understood, the predicted abundances of elements near the nucleosynthesis endpoint, in particular Ar and Ca, appear to sometimes be in disagreement with astronomical observations of the spectra of nova ejecta.Purpose: One possible source of the discrepancies between model predictions and astronomical observations is nuclear reaction data. Most reaction rates near the nova endpoint are estimated only from statistical model calculations, which carry large uncertainties. For certain key reactions, these rate uncertainties translate into large uncertainties in nucleosynthesis predictions. In particular, the 38 K (p, γ) 39 Ca reaction has been identified as having a significant influence on Ar, K, and Ca production. In order to constrain the rate of this reaction, we have performed a direct measurement of the strengths of three candidate ℓ = 0 resonances within the Gamow window for nova burning, at 386 ± 10 keV, 515 ± 10 keV, and 689 ± 10 keV. Method:The experiment was performed in inverse kinematics using a beam of unstable 38 K impinged on a windowless hydrogen gas target. The 39 Ca recoils and prompt γ rays from 38 K (p, γ) 39 Ca reactions were detected in coincidence using a recoil mass separator and a bismuth-germanate scintillator array, respectively.Results: For the 689 keV resonance, we observed a clear recoil-γ coincidence signal and extracted resonance strength and energy values of 120 +50 −30 (stat.) +20 −60 (sys.) meV and 679 +2 −1 (stat.) ± 1 (sys.) keV, respectively. We also performed a singles analysis of the recoil data alone, extracting a resonance strength of 120 ± 20 (stat.) ± 15 (sys.) meV, consistent with the coincidence result. For the 386 keV and 515 keV resonances, we extract 90% confidence level upper limits of 2.54 meV and 18.4 meV, respectively. Conclusions:We have established a new recommended 38 K(p, γ) 39 Ca rate based on experimental information, which reduces overall uncertainties near the peak temperatures of nova burning by a factor of ∼ 250. Using the rate obtained in this work in model calculations of the hottest oxygen-neon novae reduces overall uncertainties on Ar, K, and Ca synthesis to factors of 15 or less in all cases.

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Section: Methodsmentioning

confidence: 99%

Section: Singles Analysismentioning

confidence: 99%

Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Christian,

Lotay,

Ruiz

et al. 2018

Preprint

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“…To begin, we performed simulations for the z distribution of the highest energy γ rays using different resonance energies (13 values, spanning from E r = 1457.8 to 1469.8 keV) and a fixed beam energy of 3.675 MeV and spread equal to the experimental one, with the standard DRAGON GEANT3 simulation package 1 [21]. The GEANT input file included nuclear level information, such as lifetimes and γ branching ratios, from Reference [22].…”

Section: Log-likelihood Analysis For E R and ωγmentioning

confidence: 99%

Beyond the acceptance limit of DRAGON: The case of the 6Li(α,γ)
Psaltis
¹
,
Chen
²
,
Connolly
³

et al. 2021
Nuclear Instruments and Methods in Physics Research Section A:
3
0
2
0
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Radiative capture reactions play a pivotal role for our understanding of the origin of the elements in the cosmos. Recoil separators provide an effective way to study these reactions, in inverse kinematics, and take advantage of the use of radioactive ion beams. However, a limiting factor in the study of radiative capture reactions in inverse kinematics is the momentum spread of the product nuclei, which can result in an angular spread larger than the geometric acceptance of the separator. The DRAGON facility at TRIUMF is a versatile recoil separator, designed to study radiative capture reactions relevant to astrophysics in the A∼10-30 region. In this work we present the first attempt to study with DRAGON a reaction, 6 Li(α, γ) 10 B, for which the recoil angular spread exceeds DRAGON's acceptance. Our result is in good agreement with the literature value, showing that DRAGON can measure resonance strengths of astrophysically important reactions even when not all the recoils enter the separator.

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“…a relative uncertainty of 0.002%. The BGO efficiency was calculated from a Geant3 simulation [39], with the branching ratios for the decay of the 3.54 MeV state in 21 Na taken from Ref. [40].…”

Section: Resonance Strength Calculationmentioning

confidence: 99%

Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator

et al. 2014

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The DRAGON recoil mass separator at Triumf exists to study radiative proton and alpha capture reactions, which are important in a variety of astrophysical scenarios. DRAGON experiments require a data acquisition system that can be triggered on either reaction product (γ ray or heavy ion), with the additional requirement of being able to promptly recognize coincidence events in an online environment. To this end, we have designed and implemented a new data acquisition system for DRAGON which consists of two independently triggered readouts. Events from both systems are recorded with timestamps from a 20 MHz clock that are used to tag coincidences in the earliest possible stage of the data analysis. Here we report on the design, implementation, and commissioning of the new DRAGON data acquisition system, including the hardware, trigger logic, coincidence reconstruction algorithm, and live time considerations. We also discuss the results of an experiment commissioning the new system, which measured the strength of the Ec.m. = 1113 keV resonance in the 20 Ne(p, γ) 21 Na radiative proton capture reaction.

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Efficiency calibration measurement and GEANT simulation of the DRAGON BGO gamma ray array at TRIUMF.

Cited by 4 publications

References 33 publications

Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Beyond the acceptance limit of DRAGON: The case of the 6Li(α,γ)
Psaltis
¹
,
Chen
²
,
Connolly
³

et al. 2021
Nuclear Instruments and Methods in Physics Research Section A:
3
0
2
0
View full text Add to dashboard Cite

Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator

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Efficiency calibration measurement and GEANT simulation of the DRAGON BGO gamma ray array at TRIUMF.

Cited by 4 publications

References 33 publications

Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Direct Measurement of Astrophysically Important Resonances in $^{38}\mathrm{K}(p, γ){}^{39}\mathrm{Ca}$

Beyond the acceptance limit of DRAGON: The case of the 6Li(α,γ)Psaltis1, Chen2, Connolly3 et al. 2021Nuclear Instruments and Methods in Physics Research Section A: 3020View full textAdd to dashboardCite

Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator

Contact Info

Product

Resources

About

Beyond the acceptance limit of DRAGON: The case of the 6Li(α,γ)
Psaltis
¹
,
Chen
²
,
Connolly
³

et al. 2021
Nuclear Instruments and Methods in Physics Research Section A:
3
0
2
0
View full text Add to dashboard Cite