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Title: Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Abstract

Here, 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 th reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective 239Pu fission fractions F 239 from 0.25 to 0.35, Daya Bay measures an average IBD yield ¯σf of (5.90±0.13)×10 –43 cm 2/fission and a fuel-dependent variation in the IBD yield, dσ f/dF 239, of (–1.86±0.18)×10 –43 cm 2/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the 239Pu fission fraction at 10 standard deviations. The variation in IBD yield is 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 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect tomore » predictions does not result from equal fractional deficits from the primary fission isotopes 235U, 239Pu, 238U, and 241Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10 –43 cm 2/fission have been determined for the two dominant fission parent isotopes 235U and 239Pu. A 7.8% discrepancy between the observed and predicted 235U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.« less

Authors:
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Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1375196
Report Number(s):
BNL-114025-2017-JA
Journal ID: ISSN 0031-9007; PRLTAO; R&D Project: PO-022; KA2201020; TRN: US1702794
Grant/Contract Number:
SC00112704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 118; Journal Issue: 25; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; antineutrino; flux; energy; spectrum

Citation Formats

An, F. P., Balantekin, A. B., Band, H. R., Bishai, M., Blyth, S., Cao, D., Cao, G. F., Cao, J., Chan, Y. L., Chang, J. F., Chang, Y., Chen, H. S., Chen, Q. Y., Chen, S. M., Chen, Y. X., Chen, Y., Cheng, J., Cheng, Z. K., Cherwinka, J. J., Chu, M. C., Chukanov, A., Cummings, J. P., Ding, Y. Y., Diwan, M. V., Dolgareva, M., Dove, J., Dwyer, D. A., Edwards, W. R., Gill, R., Gonchar, M., Gong, G. H., Gong, H., Grassi, M., Gu, W. Q., Guo, L., Guo, X. H., Guo, Y. H., Guo, Z., Hackenburg, R. W., Hans, S., He, M., Heeger, K. M., Heng, Y. K., Higuera, A., Hsiung, Y. B., Hu, B. Z., Hu, T., Huang, E. C., Huang, H. X., Huang, X. T., Huang, Y. B., Huber, P., Huo, W., Hussain, G., Jaffe, D. E., Jen, K. L., Ji, X. P., Ji, X. L., Jiao, J. B., Johnson, R. A., Jones, D., Kang, L., Kettell, S. H., Khan, A., Kohn, S., Kramer, M., Kwan, K. K., Kwok, M. W., Langford, T. J., Lau, K., Lebanowski, L., Lee, J., Lee, J. H. C., Lei, R. T., Leitner, R., Leung, J. K. C., Li, C., Li, D. J., Li, F., Li, G. S., Li, Q. J., Li, S., Li, S. C., Li, W. D., Li, X. N., Li, X. Q., Li, Y. F., Li, Z. B., Liang, H., Lin, C. J., Lin, G. L., Lin, S., Lin, S. K., Lin, Y. -C., Ling, J. J., Link, J. M., Littenberg, L., Littlejohn, B. R., Liu, J. L., Liu, J. C., Loh, C. W., Lu, C., Lu, H. Q., Lu, J. S., Luk, K. B., Ma, X. Y., Ma, X. B., Ma, Y. Q., Malyshkin, Y., Martinez Caicedo, D. A., McDonald, K. T., McKeown, R. D., Mitchell, I., Nakajima, Y., Napolitano, J., Naumov, D., Naumova, E., Ngai, H. Y., Ochoa-Ricoux, J. P., Olshevskiy, A., Pan, H. -R., Park, J., Patton, S., Pec, V., Peng, J. C., Pinsky, L., Pun, C. S. J., Qi, F. Z., Qi, M., Qian, X., Qiu, R. M., Raper, N., Ren, J., Rosero, R., Roskovec, B., Ruan, X. C., Steiner, H., Stoler, P., Sun, J. L., Tang, W., Taychenachev, D., Treskov, K., Tsang, K. V., Tull, C. E., Viaux, N., Viren, B., Vorobel, V., Wang, C. H., Wang, M., Wang, N. Y., Wang, R. G., Wang, W., Wang, X., Wang, Y. F., Wang, Z., Wang, Z., Wang, Z. M., Wei, H. Y., Wen, L. J., Whisnant, K., White, C. G., Whitehead, L., Wise, T., Wong, H. L. H., Wong, S. C. F., Worcester, E., Wu, C. -H., Wu, Q., Wu, W. J., Xia, D. M., Xia, J. K., Xing, Z. Z., Xu, J. L., Xu, Y., Xue, T., Yang, C. G., Yang, H., Yang, L., Yang, M. S., Yang, M. T., Yang, Y. Z., Ye, M., Ye, Z., Yeh, M., Young, B. L., Yu, Z. Y., Zeng, S., Zhan, L., Zhang, C., Zhang, C. C., Zhang, H. H., Zhang, J. W., Zhang, Q. M., Zhang, R., Zhang, X. T., Zhang, Y. M., Zhang, Y. X., Zhang, Y. M., Zhang, Z. J., Zhang, Z. Y., Zhang, Z. P., Zhao, J., Zhou, L., Zhuang, H. L., and Zou, J. H.. Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.118.251801.
An, F. P., Balantekin, A. B., Band, H. R., Bishai, M., Blyth, S., Cao, D., Cao, G. F., Cao, J., Chan, Y. L., Chang, J. F., Chang, Y., Chen, H. S., Chen, Q. Y., Chen, S. M., Chen, Y. X., Chen, Y., Cheng, J., Cheng, Z. K., Cherwinka, J. J., Chu, M. C., Chukanov, A., Cummings, J. P., Ding, Y. Y., Diwan, M. V., Dolgareva, M., Dove, J., Dwyer, D. A., Edwards, W. R., Gill, R., Gonchar, M., Gong, G. H., Gong, H., Grassi, M., Gu, W. Q., Guo, L., Guo, X. H., Guo, Y. H., Guo, Z., Hackenburg, R. W., Hans, S., He, M., Heeger, K. M., Heng, Y. K., Higuera, A., Hsiung, Y. B., Hu, B. Z., Hu, T., Huang, E. C., Huang, H. X., Huang, X. T., Huang, Y. B., Huber, P., Huo, W., Hussain, G., Jaffe, D. E., Jen, K. L., Ji, X. P., Ji, X. L., Jiao, J. B., Johnson, R. A., Jones, D., Kang, L., Kettell, S. H., Khan, A., Kohn, S., Kramer, M., Kwan, K. K., Kwok, M. W., Langford, T. J., Lau, K., Lebanowski, L., Lee, J., Lee, J. H. C., Lei, R. T., Leitner, R., Leung, J. K. C., Li, C., Li, D. J., Li, F., Li, G. S., Li, Q. J., Li, S., Li, S. C., Li, W. D., Li, X. N., Li, X. Q., Li, Y. F., Li, Z. B., Liang, H., Lin, C. J., Lin, G. L., Lin, S., Lin, S. K., Lin, Y. -C., Ling, J. J., Link, J. M., Littenberg, L., Littlejohn, B. R., Liu, J. L., Liu, J. C., Loh, C. W., Lu, C., Lu, H. Q., Lu, J. S., Luk, K. B., Ma, X. Y., Ma, X. B., Ma, Y. Q., Malyshkin, Y., Martinez Caicedo, D. A., McDonald, K. T., McKeown, R. D., Mitchell, I., Nakajima, Y., Napolitano, J., Naumov, D., Naumova, E., Ngai, H. Y., Ochoa-Ricoux, J. P., Olshevskiy, A., Pan, H. -R., Park, J., Patton, S., Pec, V., Peng, J. C., Pinsky, L., Pun, C. S. J., Qi, F. Z., Qi, M., Qian, X., Qiu, R. M., Raper, N., Ren, J., Rosero, R., Roskovec, B., Ruan, X. C., Steiner, H., Stoler, P., Sun, J. L., Tang, W., Taychenachev, D., Treskov, K., Tsang, K. V., Tull, C. E., Viaux, N., Viren, B., Vorobel, V., Wang, C. H., Wang, M., Wang, N. Y., Wang, R. G., Wang, W., Wang, X., Wang, Y. F., Wang, Z., Wang, Z., Wang, Z. M., Wei, H. Y., Wen, L. J., Whisnant, K., White, C. G., Whitehead, L., Wise, T., Wong, H. L. H., Wong, S. C. F., Worcester, E., Wu, C. -H., Wu, Q., Wu, W. J., Xia, D. M., Xia, J. K., Xing, Z. Z., Xu, J. L., Xu, Y., Xue, T., Yang, C. G., Yang, H., Yang, L., Yang, M. S., Yang, M. T., Yang, Y. Z., Ye, M., Ye, Z., Yeh, M., Young, B. L., Yu, Z. Y., Zeng, S., Zhan, L., Zhang, C., Zhang, C. C., Zhang, H. H., Zhang, J. W., Zhang, Q. M., Zhang, R., Zhang, X. T., Zhang, Y. M., Zhang, Y. X., Zhang, Y. M., Zhang, Z. J., Zhang, Z. Y., Zhang, Z. P., Zhao, J., Zhou, L., Zhuang, H. L., & Zou, J. H.. Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay. United States. doi:10.1103/PhysRevLett.118.251801.
An, F. P., Balantekin, A. B., Band, H. R., Bishai, M., Blyth, S., Cao, D., Cao, G. F., Cao, J., Chan, Y. L., Chang, J. F., Chang, Y., Chen, H. S., Chen, Q. Y., Chen, S. M., Chen, Y. X., Chen, Y., Cheng, J., Cheng, Z. K., Cherwinka, J. J., Chu, M. C., Chukanov, A., Cummings, J. P., Ding, Y. Y., Diwan, M. V., Dolgareva, M., Dove, J., Dwyer, D. A., Edwards, W. R., Gill, R., Gonchar, M., Gong, G. H., Gong, H., Grassi, M., Gu, W. Q., Guo, L., Guo, X. H., Guo, Y. H., Guo, Z., Hackenburg, R. W., Hans, S., He, M., Heeger, K. M., Heng, Y. K., Higuera, A., Hsiung, Y. B., Hu, B. Z., Hu, T., Huang, E. C., Huang, H. X., Huang, X. T., Huang, Y. B., Huber, P., Huo, W., Hussain, G., Jaffe, D. E., Jen, K. L., Ji, X. P., Ji, X. L., Jiao, J. B., Johnson, R. A., Jones, D., Kang, L., Kettell, S. H., Khan, A., Kohn, S., Kramer, M., Kwan, K. K., Kwok, M. W., Langford, T. J., Lau, K., Lebanowski, L., Lee, J., Lee, J. H. C., Lei, R. T., Leitner, R., Leung, J. K. C., Li, C., Li, D. J., Li, F., Li, G. S., Li, Q. J., Li, S., Li, S. C., Li, W. D., Li, X. N., Li, X. Q., Li, Y. F., Li, Z. B., Liang, H., Lin, C. J., Lin, G. L., Lin, S., Lin, S. K., Lin, Y. -C., Ling, J. J., Link, J. M., Littenberg, L., Littlejohn, B. R., Liu, J. L., Liu, J. C., Loh, C. W., Lu, C., Lu, H. Q., Lu, J. S., Luk, K. B., Ma, X. Y., Ma, X. B., Ma, Y. Q., Malyshkin, Y., Martinez Caicedo, D. A., McDonald, K. T., McKeown, R. D., Mitchell, I., Nakajima, Y., Napolitano, J., Naumov, D., Naumova, E., Ngai, H. Y., Ochoa-Ricoux, J. P., Olshevskiy, A., Pan, H. -R., Park, J., Patton, S., Pec, V., Peng, J. C., Pinsky, L., Pun, C. S. J., Qi, F. Z., Qi, M., Qian, X., Qiu, R. M., Raper, N., Ren, J., Rosero, R., Roskovec, B., Ruan, X. C., Steiner, H., Stoler, P., Sun, J. L., Tang, W., Taychenachev, D., Treskov, K., Tsang, K. V., Tull, C. E., Viaux, N., Viren, B., Vorobel, V., Wang, C. H., Wang, M., Wang, N. Y., Wang, R. G., Wang, W., Wang, X., Wang, Y. F., Wang, Z., Wang, Z., Wang, Z. M., Wei, H. Y., Wen, L. J., Whisnant, K., White, C. G., Whitehead, L., Wise, T., Wong, H. L. H., Wong, S. C. F., Worcester, E., Wu, C. -H., Wu, Q., Wu, W. J., Xia, D. M., Xia, J. K., Xing, Z. Z., Xu, J. L., Xu, Y., Xue, T., Yang, C. G., Yang, H., Yang, L., Yang, M. S., Yang, M. T., Yang, Y. Z., Ye, M., Ye, Z., Yeh, M., Young, B. L., Yu, Z. Y., Zeng, S., Zhan, L., Zhang, C., Zhang, C. C., Zhang, H. H., Zhang, J. W., Zhang, Q. M., Zhang, R., Zhang, X. T., Zhang, Y. M., Zhang, Y. X., Zhang, Y. M., Zhang, Z. J., Zhang, Z. Y., Zhang, Z. P., Zhao, J., Zhou, L., Zhuang, H. L., and Zou, J. H.. 2017. "Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay". United States. doi:10.1103/PhysRevLett.118.251801.
@article{osti_1375196,
title = {Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay},
author = {An, F. P. and Balantekin, A. B. and Band, H. R. and Bishai, M. and Blyth, S. and Cao, D. and Cao, G. F. and Cao, J. and Chan, Y. L. and Chang, J. F. and Chang, Y. and Chen, H. S. and Chen, Q. Y. and Chen, S. M. and Chen, Y. X. and Chen, Y. and Cheng, J. and Cheng, Z. K. and Cherwinka, J. J. and Chu, M. C. and Chukanov, A. and Cummings, J. P. and Ding, Y. Y. and Diwan, M. V. and Dolgareva, M. and Dove, J. and Dwyer, D. A. and Edwards, W. R. and Gill, R. and Gonchar, M. and Gong, G. H. and Gong, H. and Grassi, M. and Gu, W. Q. and Guo, L. and Guo, X. H. and Guo, Y. H. and Guo, Z. and Hackenburg, R. W. and Hans, S. and He, M. and Heeger, K. M. and Heng, Y. K. and Higuera, A. and Hsiung, Y. B. and Hu, B. Z. and Hu, T. and Huang, E. C. and Huang, H. X. and Huang, X. T. and Huang, Y. B. and Huber, P. and Huo, W. and Hussain, G. and Jaffe, D. E. and Jen, K. L. and Ji, X. P. and Ji, X. L. and Jiao, J. B. and Johnson, R. A. and Jones, D. and Kang, L. and Kettell, S. H. and Khan, A. and Kohn, S. and Kramer, M. and Kwan, K. K. and Kwok, M. W. and Langford, T. J. and Lau, K. and Lebanowski, L. and Lee, J. and Lee, J. H. C. and Lei, R. T. and Leitner, R. and Leung, J. K. C. and Li, C. and Li, D. J. and Li, F. and Li, G. S. and Li, Q. J. and Li, S. and Li, S. C. and Li, W. D. and Li, X. N. and Li, X. Q. and Li, Y. F. and Li, Z. B. and Liang, H. and Lin, C. J. and Lin, G. L. and Lin, S. and Lin, S. K. and Lin, Y. -C. and Ling, J. J. and Link, J. M. and Littenberg, L. and Littlejohn, B. R. and Liu, J. L. and Liu, J. C. and Loh, C. W. and Lu, C. and Lu, H. Q. and Lu, J. S. and Luk, K. B. and Ma, X. Y. and Ma, X. B. and Ma, Y. Q. and Malyshkin, Y. and Martinez Caicedo, D. A. and McDonald, K. T. and McKeown, R. D. and Mitchell, I. and Nakajima, Y. and Napolitano, J. and Naumov, D. and Naumova, E. and Ngai, H. Y. and Ochoa-Ricoux, J. P. and Olshevskiy, A. and Pan, H. -R. and Park, J. and Patton, S. and Pec, V. and Peng, J. C. and Pinsky, L. and Pun, C. S. J. and Qi, F. Z. and Qi, M. and Qian, X. and Qiu, R. M. and Raper, N. and Ren, J. and Rosero, R. and Roskovec, B. and Ruan, X. C. and Steiner, H. and Stoler, P. and Sun, J. L. and Tang, W. and Taychenachev, D. and Treskov, K. and Tsang, K. V. and Tull, C. E. and Viaux, N. and Viren, B. and Vorobel, V. and Wang, C. H. and Wang, M. and Wang, N. Y. and Wang, R. G. and Wang, W. and Wang, X. and Wang, Y. F. and Wang, Z. and Wang, Z. and Wang, Z. M. and Wei, H. Y. and Wen, L. J. and Whisnant, K. and White, C. G. and Whitehead, L. and Wise, T. and Wong, H. L. H. and Wong, S. C. F. and Worcester, E. and Wu, C. -H. and Wu, Q. and Wu, W. J. and Xia, D. M. and Xia, J. K. and Xing, Z. Z. and Xu, J. L. and Xu, Y. and Xue, T. and Yang, C. G. and Yang, H. and Yang, L. and Yang, M. S. and Yang, M. T. and Yang, Y. Z. and Ye, M. and Ye, Z. and Yeh, M. and Young, B. L. and Yu, Z. Y. and Zeng, S. and Zhan, L. and Zhang, C. and Zhang, C. C. and Zhang, H. H. and Zhang, J. W. and Zhang, Q. M. and Zhang, R. and Zhang, X. T. and Zhang, Y. M. and Zhang, Y. X. and Zhang, Y. M. and Zhang, Z. J. and Zhang, Z. Y. and Zhang, Z. P. and Zhao, J. and Zhou, L. and Zhuang, H. L. and Zou, J. H.},
abstractNote = {Here, 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 GWth reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective 239Pu fission fractions F239 from 0.25 to 0.35, Daya Bay measures an average IBD yield ¯σf of (5.90±0.13)×10–43 cm2/fission and a fuel-dependent variation in the IBD yield, dσf/dF239, of (–1.86±0.18)×10–43 cm2/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the 239Pu fission fraction at 10 standard deviations. The variation in IBD yield is 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 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes 235U, 239Pu, 238U, and 241Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10–43 cm2/fission have been determined for the two dominant fission parent isotopes 235U and 239Pu. A 7.8% discrepancy between the observed and predicted 235U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.},
doi = {10.1103/PhysRevLett.118.251801},
journal = {Physical Review Letters},
number = 25,
volume = 118,
place = {United States},
year = 2017,
month = 6
}

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  • This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9~GW th nuclear reactors with six detectors deployed in two near (effective baselines 512~m and 561~m) and one far (1,579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296,721 and 41,589 inverse beta decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55 ± 0.04) × 10 –18 cm 2/GW/day or (5.92 ± 0.14) × 10 –43 cm 2/fission. This flux measurement is consistent with previous short-baseline reactor antineutrino experimentsmore » and is 0.946 ± 0.022 (0.991 ± 0.023) relative to the flux predicted with the Huber+Mueller (ILL+Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ~4σ between 4-6 MeV. Furthermore, a reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.« less
  • Here, a new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GW th nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946 ± 0.020 (0.992more » ± 0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4$-$6 MeV was found in the measured spectrum, with a local significance of 4.4σ. Finally, a reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.« less
  • This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10-18 cm2 GW-1 day-1 or (5.92±0.14) ×10-43 cm2 fission-1. This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023)more » relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ~4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.« less