The PROSPECT physics program

Ashenfelter, J.; Balantekin, A. B.; Band, H. R.; Barclay, Glen St. J.; Bass, C.D.; Berish, D.; Bignell, L.J.; Bowden, N. S.; Bowes, Alyssa; Brodsky, J.; Bryan, C. D.; Cherwinka, J. J.; Chu, Ran; Classen, T.; Commeford, Kelley; Conant, A.J.; Davee, D.; Dean, D. J.; Deichert, G.; Diwan, M. V.; Dolinski, M. J.; Dolph, J.; DuVernois, Michael; Erickson, Anna; Febbraro, M.; Gaison, Jeremy; Galindo-Uribarri, A.; Gilje, K.; Glenn, A.; Goddard, Brennan; Green, M. P.; Hackett, B.; Han, K.; Hans, S.; Heeger, K. M.; Heffron, B.; Insler, J.; Jaffe, D. E.; Jones, D.; Langford, T.; Littlejohn, B. R.; Caicedo, D. A. Martínez; Matta, J. T.; McKeown, R. D.; Mendenhall, M. P.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Neilson, R.; Nikkel, J.; Norcini, D.; Pushin, D. A.; Qian, X.; Romero, Enrique Pérez; Rosero, R.; Seilhan, B.; Sharma, R.; Sheets, S. A.; Surukuchi, P. T.; Trinh, C.; Varner, R. L.; Viren, B.; Wang, W; White, B. R.; White, C.; Wilhelmi, J.; Williams, C. W.; Wise, T.; Yao, Haifeng; Yeh, M.; Yen, Y.-R.; Zangakis, G.; Zhang, C; Zhang, X

doi:10.1088/0954-3899/43/11/113001

Cited by 79 publications

(106 citation statements)

References 80 publications

(198 reference statements)

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“…Improvement in Daya Bay's measurements of σ 235 and σ 239 can be achieved with increased statistics and with a reduction of the ADcorrelated IBD detection efficiency systematic uncertainty. Future short-baseline experiments at highly enriched uranium reactors [34][35][36] PRL 118, 251801 (2017) P H Y S I C A L R E V I E W L E T T E R S week ending 23 JUNE 2017 …”

Section: 251801 (2017) P H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

An¹,

Balantekin²,

Band³

et al. 2017

Phys. Rev. Lett.

172

225

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The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW$_{\textrm{th}}$ reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective $^{239}$Pu fission fractions, $F_{239}$, from 0.25 to 0.35, Daya Bay measures an average IBD yield, $\bar{\sigma}_f$, of $(5.90 \pm 0.13) \times 10^{-43}$ cm$^2$/fission and a fuel-dependent variation in the IBD yield, $d\sigma_f/dF_{239}$, of $(-1.86 \pm 0.18) \times 10^{-43}$ cm$^2$/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the $^{239}$Pu fission fraction at 10 standard deviations. The variation in IBD yield was found to be energy-dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1$\sigma$. This discrepancy indicates that an overall deficit in measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes $^{235}$U, $^{239}$Pu, $^{238}$U, and $^{241}$Pu. Based on measured IBD yield variations, yields of $(6.17 \pm 0.17)$ and $(4.27 \pm 0.26) \times 10^{-43}$ cm$^2$/fission have been determined for the two dominant fission parent isotopes $^{235}$U and $^{239}$Pu. A 7.8% discrepancy between the observed and predicted $^{235}$U yield suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure

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Section: 251801 (2017) P H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

An¹,

Balantekin²,

Band³

et al. 2017

Phys. Rev. Lett.

172

225

View full text Add to dashboard Cite

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“…However, while these combined fits suggest a preference for models including sterile neutrinos, the significant uncertainties in the reactor rate measurements and the high goodness-of-fits observed for models both with and without sterile neutrinos make it clear that the search for the explanation of the reactor antineutrino anomaly [9] still remains open. We hope that it will be solved soon by the new short-baseline reactor neutrino experiments which will measure the reactor antineutrino flux from reactors with different fuel compositions: highly enriched 235 U research reactors for PROSPECT [31], SoLid [32], and STEREO [33], and commercial reactors with mixed fuel compositions for DANSS [34] and Neutrino-4 [35].…”

Section: Jhep10(2017)143mentioning

confidence: 99%

Reactor fuel fraction information on the antineutrino anomaly

Giunti

Laveder

et al. 2017

J. High Energ. Phys.

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Abstract:We analyzed the evolution data of the Daya Bay reactor neutrino experiment in terms of short-baseline active-sterile neutrino oscillations taking into account the theoretical uncertainties of the reactor antineutrino fluxes. We found that oscillations are disfavored at 2.6σ with respect to a suppression of the 235 U reactor antineutrino flux and at 2.5σ with respect to variations of the 235 U and 239 Pu fluxes. On the other hand, the analysis of the rates of the short-baseline reactor neutrino experiments favor active-sterile neutrino oscillations and disfavor the suppression of the 235 U flux at 3.1σ and variations of the 235 U and 239 Pu fluxes at 2.8σ. We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the 235 U or 239 Pu fluxes in addition to active-sterile neutrino oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for oscillations with respect to variations of the 235 U and 239 Pu fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the 239 Pu flux and relatively large oscillations.

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“…[29] and by the hint of a correlation in the RENO experiment [22]. The new reactor experiments PROSPECT [30], SoLid [31], and STEREO [32] which are in preparation for the search of short-baseline neutrino oscillations with highly enriched 235 U research reactors, will improve the determination of the 235 U electron antineutrino flux. Since the 238 U and 241 Pu fuel composition in power reactors is small (see Table 1 of Ref.…”

mentioning

confidence: 99%

Improved determination of the U235 and Pu239<

Giunti

2017

Phys. Rev. D

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We present the results of a combined fit of the reactor antineutrino rates and the Daya Bay measurement of σ f,235 and σ f,239 . The combined fit leads to a better determination of the two cross sections per fission: σ f,235 = 6.29 ± 0.08 and σ f,239 = 4.24 ± 0.21 in units of 10 −43 cm 2 /fission, with respective uncertainties of about 1.2% and 4.9%. Since the respective deviations from the theoretical cross sections per fission are 2.5σ and 0.7σ, we conclude that, if the reactor antineutrino anomaly is not due to active-sterile neutrino oscillations, it is likely that it can be solved with a revaluation of the 235 U reactor antineutrino flux. However, the 238 U, 239 Pu, and 241 Pu fluxes, which have larger uncertainties, could also be significantly different from the theoretical predictions.The flux of electron antineutrinos produced in nuclear reactors is generated by the β decays of the fission products of 235 U, 238 U, 239 Pu, and 241 Pu. The 2011 recalculation [1, 2] of the four fluxes led to the discovery of the reactor antineutrino anomaly [3], which is a deficit of the rate of electron antineutrinos measured in several reactor neutrino experiments. There are two known possible explanations of the reactor antineutrino anomaly: 1) a miscalculation of one or more of the four electron antineutrino fluxes [4,5] and 2) active-sterile neutrino oscillations (see Ref.[6] and references therein). In this paper we consider the first possibility and we present an improvement of the results presented in Refs. [4,5] The cross section per fission σ f,235 of the 235 U electron antineutrino flux was determined in Ref.[4] with a fit of the reactor rates by taking into account the different fuel compositions. Recently the Daya Bay Collaboration presented a determination of σ f,235 and σ f,239 obtained by measuring the correlations between the reactor core fuel evolution and the changes in the reactor antineutrino flux and energy spectrum [5]. In this paper we present a combined fit of the reactor rates and the Daya Bay measurement of σ f,235 and σ f,239 which leads to a better determination of both cross sections per fission.In the analysis of the reactor rates, we consider the theoretical ratios [4]where f a k is the antineutrino flux fraction from the fission of the isotope with atomic mass k and the coefficient r k is the corresponding correction of the theoretical cross section per fission σ SH f,k which is needed to fit the data (k = 235, 238, 239, 241, denotes, respectively We analyze the data of the reactor rates with the leastsquares statisticwhere R exp a are the measured reactor rates listed in Table 1 of Ref. [6] and V R is the covariance matrix constructed with the corresponding uncertainties. The second term in Eq. (2) serves to keep under control the variation of the rates of the minor fissionable isotopes 238 U and 241 Pu, which are not well determined by the fit [4]. We consider ∆r 238 = 15% and ∆r 241 = 10%, which are significantly larger than the nominal theoretical uncertainties (respectively, 8.15% and...

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The PROSPECT physics program

Cited by 79 publications

References 80 publications

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Reactor fuel fraction information on the antineutrino anomaly

Improved determination of the U235 and Pu239<

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