Abstract
Investigation of spatial parity in reactions of polarized neutrons with light nuclei is an important topic in the framework of exploring the fundamental problem of understanding the manifestation of the weak interaction in nuclear reactions and for estimating the parameters of the weak nucleon–nucleon interaction. In this paper, the ongoing experimental program of highly sensitive and high-precision measurements of P‑odd asymmetries in the reactions of polarized thermal and cold neutrons with lithium and boron nuclei is reviewed. Within this program, the coefficients of P-odd asymmetry of reaction products in the reactions induced by cold- and thermal-neutrons on the isotopes of light nuclei 6Li and 10B were measured with record-high sensitivity ~10–8 as \(\alpha _{{P{\text{ - odd}}}}^{{^{{\text{6}}}{\text{Li}}{\text{,exp}}}} = - (8.8 \pm 2.1) \times {{10}^{{ - 8}}}\), \(\alpha _{{P{\text{ - odd}}}}^{{^{{10}}{\text{B}},\gamma ,\exp }} = (0.0 \pm {{2.6}_{{{\text{stat}}.}}} \pm {{1.1}_{{{\text{syst}}{\text{.}}}}}) \times {{10}^{{ - 8}}},\) and \(\alpha _{{P{\text{ - odd}}}}^{{{{\alpha }_{0}} + {{\alpha }_{1}}{{,}^{{10}}}B,\exp }} = - (11.2 \pm 3.4) \times {{10}^{{ - 8}}}\). For the first time ever, nonzero values were obtained for two of these asymmetries. Our data for tritium emission in the \(^{6}{\text{Li(}}n,a{{)}^{3}}{\text{H}}\) reaction and γ emission in the \(^{{10}}{\text{B}}{{(n,a)}^{{74}}}{\text{Li}}^{*} \to \gamma \to {{\,}^{7}}{\kern 1pt} {\text{Li(gr}}{\text{.st}}{\text{.)}}\) reaction agree with those of other experiments when interpreted within the cluster model, but rule out the so-called “best DDH values” of weak-interaction coupling constants. Interpreting the data on these reactions relying on “first principles” only would be highly desirable.
Similar content being viewed by others
REFERENCES
Steven Weinberg, “Conceptual foundations of the unified theory of weak and electromagnetic interactions,” in Nobel Lectures, Physics 1971–1980, edited by Stig Lundquist (World Scientific, Singapore, 1992).
D. Cline, A. K. Mann, and C. Rubbia, “The detection of neutral weak currents, ” Sci. Am. 231, 108 (1974).
L. M. Barkov, M. S. Zolotarev, and I. B. Khriplovich, “Observation of parity nonconservation in atoms,” Sov. Phys. Uspekhi 23, 713–731 (1980).
E. G. Adelberger and W. C. Haxton, “Parity violation in the nucleon interaction,” Ann. Rev. Nucl. Part. Sci. 35, 501 (1985).
B. Desplanques, “Parity-non-conservation in nuclear forces at low energy: Phenomenology and questions,” Phys. Rep. 297, 1 (1998).
B. Desplanques, J. F. Donoghue, and B. R. Holstein, “Unified treatment of the parity violating nuclear force,” Ann. Phys. 124, 449 (1980).
N. Kaiser and U. G. Meissner, “The weak pion-nucleon vertex revisited,” Nucl. Phys. A 489, 671 (1988).
N. Kaiser and U. G. Meissner, “Novel calculation of weak meson-nucleon couplings,” Nucl. Phys. A 499, 699 (1989).
S.-L. Zhu, C. M. Maekawa, B. R. Holstein, M. J. Ramsey-Musolf, and U. van Kolck, “Nuclear parity violation in effective field theory,” Nucl. Phys. A 748, 435 (2005).
M. J. Ramsey-Musolf and S. A. Page, “Hadronic parity violation: A new view through the looking glass,” Ann. Rev. Nucl. Part. Sci. 58, 1 (2006).
C.-P. Liu, “Parity-violating observables of two-nucleon systems in effective field theory,” Phys. Rev. C 75, 065501 (2007).
D. R. Phillips, D. Samart, and C. Schat, “Parity-violating nucleon–force in the 1/Nc expansion,” Phys. Rev. Lett. 114, 062301 (2015).
M. R. Schindler, R. P. Springer, and J. Vanasse, “Large-Nc limit reduces the number of independent few-body parity-violating low-energy constants in pionless effective field theory,” Phys. Rev. C 93, 025502 (2016).
V. A. Vesna, Yu. M Gledenov, V. V. Nesvizhevskii, et al.,“Discovery of a P-odd effect in triton emission from the reaction 6Li(n,α)3H,” JETP Lett. 82, 463 (2005).
V. A. Vesna, Yu. M Gledenov, V. V. Nesvizhevskii, et al., “Measurement of the parity-violating triton emission asymmetry in the reaction 6Li(n,α)3H with polarized cold neutrons,” Phys. Rev. C 77, 035501 (2008).
V. A. Vesna, Yu. M Gledenov, V. V. Nesvizhevskii, et al., “Measurement of P-odd asymmetry of γ-quanta emission in the nuclear reaction 10B(n,α)7Li*→ γ + 7Li(g.s.),” Nucl. Instrum. Methods Phys. Res. A 611, 244 (2009).
V. A. Vesna, Yu. M Gledenov, V. V. Nesvizhevskii, et al., “Measurement of the parity-violating asymmetry in the reactions of cold polarized neutrons and light nuclei 6Li, 10B, ” Nucl. Phys. A 827, 425c (2009).
V. A. Vesna, Yu. M Gledenov, V. V. Nesvizhevskii, et al., “Parity-violating asymmetry in the reactions 6Li(n,α)3H and 10B(n,α)7Li*→ 7Li+ γ,” Hyper. Inter. 201, 31 (2011).
R. Balzer, R. Hennek, Ch. Jachquemart, et al., “Parity violation in proton-proton scattering at 45 MeV,” Phys. Rev. C 30, 1409 (1984).
V. Yuan, H. Fraunfelder, R. W. Harper, et al., “Measurement of parity nonconservation in the proton–proton total cross section at 800 MeV,” Phys. Rev. Lett. 57, 1680 (1986).
P. A. Krupchitsky, Fundamental Research with Polarized Slow Neutrons (Springer Verlag, Berlin–Heidelberg, 1987).
M. M. Nesterov and I. S. Okunev, «Possibility of observing weak neutral currents in light clustering nuclei,” JETP Lett. 48, 621 (1988).
S. Yu. Igashov, A. V. Sinyakov, and Yu. M. Tchuvil’sky, “Calculation of parity violation effect in 478 keV γ-transition in 7Li by resonating group model approach,” in Proceedings of the ISINN-11 (Dubna, 2004), p. 34.
H. Abele, D. Dubbers, H. Häse, et al., “Characterization of a ballistic supermirror neutron guide,” Nucl. Instrum. Methods Phys. Res. A 562, 407 (2006).
N. V. Borovikova, V. A. Vesna, A. I. Egorov, et al., “Investigation of spatial parity breakdown effects in thermal polarized neutron capture with the release of heavy charged particles,” JETP Lett. 30, 495 (1979).
Yu. M. Gledenov, I. S. Okunev, S. S. Parzhitskii, E. V. Shul’gina, and V. A. Vesna, “Investigation of P‑odd correlations in the capture of thermal polarized neutrons involving emission of secondary charged particles (technical issues),” Nucl. Instrum. Methods Phys. Res. A 350, 517 (1994).
V. A. Vesna, Yu. M. Gledenov, P. V. Sedyshev, and E. E. Shul’gina, “New version of the integrated method for measuring small effects in experiments on beams extracted from a nuclear reactor at the effect of sign switching frequency above the fundamental frequencies of the reactor power fluctuation spectrum,” J. Tech. Phys. 55, 1687–1695 (2010).
E. V. Shulgina, “Implementing a digital signal processor in the data-acquisition and control systems in experimental studies of P-odd effects in polarized-neutron collisions with nuclei towards improving their performance,” PNPI Comm. no. 2864, Gatchina, 2011 [in Russian].
V. M. Lobashov, “Prospects for experimental studies of the weak nucleon–nucleon interaction,” Yad. Fiz. 2, 957 (1965).
V. M. Lobashov, V. A. Nazarenko, L. F. Saenko, L. M. Smotritsky, and G. I. Kharkevitch, “ Parity non-conservation in the gamma decay of 181Ta,” Phys. Lett. B 25, 104 (1967).
V. A. Vesna, Yu. M. Gledenov, V. V. Nesvizhevskii, et al., “Measurements of the P-odd asymmetry of γ‑quantum emission in the 10B(n a)7Li* → 7Li (g.s.) reaction,” Bull. Russ. Acad. Sci.: Phys. 67, 125 (2003).
V. A. Vesna, Yu. M. Gledenov, I. S. Okunev, Yu. P. Popov, and E. V. Shul’gina, “Search for P-odd effects in the reactions 6Li(n,α)3H and 10B(n,α)7Li with polarized thermal neutrons,” Phys. Atom. Nucl. 59, 19 (1996).
Yu. M. Gledenov, V. A. Vesna, V. V. Nesvizhevsky, et al., “Investigation of the triton emission asymmetry in the 6Li(n,α)3H reaction with cold polarized neutrons,” in Proceedings of the ISINN-11 (Dubna, 2004), p. 26.
V. A. Vesna, Yu. M. Gledenov, V. V. Nesvizhevsky, et al., “Null experiment in the study of P-odd asymmetry of triton emission in the 6Li(n,α)3H reaction,” PNPI Preprint no. 2697, Gatchina, 2006.
S. A. Page, H. C. Evans, G. T. Ewan, et al., “Weak pion-nucleon coupling strength: New constraint from parity mixing in 18F,” Phys. Rev. C 35, 1119 (1987).
V. A. Vesna, Yu. M. Gledenov, et al., “Search for parity-violating effects in the γ-transition 7Li* → γ(M1) → 7Li (E γ = 0.478 MeV),” Phys. Atom. Nucl. 62, 522 (1999).
A. L. Barabanov, V. E. Bunakov, I. S. Guseva, and G. A. Petrov, “T-odd angular asymmetry in nuclear reactions involving sequential particle emission,” Phys. Atom. Nucl. 66, 679 (2003).
Y. G. Abov, O. N. Yermakov, A. D. Gulko, P. A. Krupchitsky, and S. S. Trostin, “Beta decay asymmetry of Li8, Ag108 and Ag110 nuclei produced in the capture of polarized thermal neutrons,” Nucl. Phys. 34, 505 (1962).
V. A. Vesna, Yu. M. Gledenov, V. V. Nesvizhevsky, et al., “Recent results on the measurement of the P-odd asymmetry of emitted γ-quanta in the 10B(n,α)7Li* → γ +7Li(g.s.) reaction with slow polarized neutrons,” in Proceedings of the ISINN-11 (Dubna, 2004), p. 52.
V. A. Vesna, Yu. M. Gledenov, V. V. Nesvizhevsky, P. V. Sedyshev, and E. V. Shulgina, “New results on P‑odd asymmetry of γ-quanta emission in 10B(n,α)7Li* → γ + 7Li(g.s.) nuclear reaction,” Eur. Phys. J. A 47, 43 (2011).
E. A. Garusov, K. A. Konoplev, P. M. Livshits et al., “Diagnostics of neutron noises in the VVR-M research reactor and their effects on the uncertainties of physical measurements,” Kernenergie 26, 68 (1983).
O. P. Sushkov and V. V. Flambaum, “Parity breaking in the interactions of neutrons with heavy nuclei,” Sov. Phys. Uspekhi 25, 1–12 (1982).
F. Ajzenberg-Selove, “Energy levels of light nuclei A = 11–12,” Nucl. Phys. A 506, 1 (1990).
I. S. Okunev, “Parity violation in interactions of light nuclei with neutrons,” in Time reversal invariance and parity violation in neutron reactions, edited by C. R. Gould, J. D. Bowman, and Yu. P. Popov (World Scientific, 1994), p. 90.
V. A. Vesna, A. I. Egorov, E. A. Kolomenskii et al, “Asymmetry of charged-particle emission in the capture of polarized thermal-neutrons by 3He and 10B nuclei,” JETP Lett. 33, 411 (1981).
Yu. M. Gledenov, V. V. Nesvizhevsky, P. V. Sedyshev et al., “First observation of P-odd asymmetry of α-particle emission in the 10B(n, α)7Li nuclear reaction,” Phys. Lett. B 769C, 111 (2017).
B. R. Holstein, “Neutrons and hadronic parity violation,” J. Phys. G 36, 104003 (2009).
Author information
Authors and Affiliations
Corresponding author
Additional information
Translated by A. Asratyan
Rights and permissions
About this article
Cite this article
Vesna, V.A., Gledenov, Y.M., Nesvizhevsky, V.V. et al. Search and Measurement of P-Odd Asymmetry in the Emission of Secondary Particles Produced in Reactions of Polarized Thermal and Cold Neutrons with Light Nuclei. Phys. Part. Nuclei 52, 1–18 (2021). https://doi.org/10.1134/S1063779621010044
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S1063779621010044