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Precise Mass Measurement of the $^{108, 110, 112, 114, 116}$Rh ground state and isomeric state(s)
B. Liu, M. Brodeur, J.A. Clark, I. Dedes, J. Dudek, F. G. Kondev, D. Ray, G. Savard, A.A. Valverde, D.P. Burdette, A.M. Houff, R. Orford, W.S. Porter, F. Rivero, K.S. Sharma, L. Varriano
Oct 02 2024 nucl-ex nucl-th arXiv:2410.00389v1

@misc{2410.00389, author = {B.~Liu and M.~Brodeur and J.A.~Clark and I.~Dedes and J.~Dudek and F.~G.~Kondev and D.~Ray and G.~Savard and A.A.~Valverde and D.P.~Burdette and A.M.~Houff and R.~Orford and W.S.~Porter and F.~Rivero and K.S.~Sharma and L.~Varriano}, title = {{P}recise {M}ass {M}easurement of the $^{108, 110, 112, 114, 116}${R}h ground state and isomeric state(s)}, year = {2024}, eprint = {2410.00389}, note = {arXiv:2410.00389v1} }
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Precise mass measurements of the $^{108, 110, 112, 114, 116}$Rh ground and isomeric states were performed using the Canadian Penning Trap at Argonne National Laboratory, showing a good agreement with recent JYFLTRAP measurements. A new possible isomeric state of $^{114}$Rh was also observed. These isotopes are part of the longest odd-odd chain of identical spin-parity assignment, of 1$^+$, spanning $^{104-118}$Rh, despite being in a region of deformation. Theoretical calculations were performed to explain this phenomenon. In addition, multiquasiparticle blocking calculations were conducted to study the configuration of low-lying states in the odd-odd Rh nuclei and elucidate the observed anomalous isomeric yield ratio of $^{114}$Rh.
Investigating the effects of precise mass measurements of Ru and Pd isotopes on machine learning mass modeling
W. S. Porter, B. Liu, D. Ray, A. A. Valverde, M. Li, M. R. Mumpower, M. Brodeur, D. P. Burdette, N. Callahan, A. Cannon, J. A. Clark, D. E. M. Hoff, A. M. Houff, F. G. Kondev, A. E. Lovell, A. T. Mohan, G. E. Morgan, C. Quick, G. Savard, K. S. Sharma, et al (2)
Sep 19 2024 nucl-ex arXiv:2409.12141v1

@misc{2409.12141, author = {W.~S.~Porter and B.~Liu and D.~Ray and A.~A.~Valverde and M.~Li and M.~R.~Mumpower and M.~Brodeur and D.~P.~Burdette and N.~Callahan and A.~Cannon and J.~A.~Clark and D.~E.~M.~Hoff and A.~M.~Houff and F.~G.~Kondev and A.~E.~Lovell and A.~T.~Mohan and G.~E.~Morgan and C.~Quick and G.~Savard and K.~S.~Sharma and T.~M.~Sprouse and L.~Varriano}, title = {{I}nvestigating the effects of precise mass measurements of {R}u and {P}d isotopes on machine learning mass modeling}, year = {2024}, eprint = {2409.12141}, howpublished = {Phys. Rev. C 110, 034321 (2024)}, doi = {10.1103/PhysRevC.110.034321}, note = {arXiv:2409.12141v1} }
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Atomic masses are a foundational quantity in our understanding of nuclear structure, astrophysics and fundamental symmetries. The long-standing goal of creating a predictive global model for the binding energy of a nucleus remains a significant challenge, however, and prompts the need for precise measurements of atomic masses to serve as anchor points for model developments. We present precise mass measurements of neutron-rich Ru and Pd isotopes performed at the Californium Rare Isotope Breeder Upgrade facility at Argonne National Laboratory using the Canadian Penning Trap mass spectrometer. The masses of $^{108}$Ru, $^{110}$Ru and $^{116}$Pd were measured to a relative mass precision $\delta m/m \approx 10^{-8}$ via the phase-imaging ion-cyclotron-resonance technique, and represent an improvement of approximately an order of magnitude over previous measurements. These mass data were used in conjunction with the physically interpretable machine learning (PIML) model, which uses a mixture density neural network to model mass excesses via a mixture of Gaussian distributions. The effects of our new mass data on a Bayesian-updating of a PIML model are presented.
Direct cross-section measurement of the weak r-process 88Sr(\alpha,n)91Zr reaction in \nu-driven winds of core collapse supernovae
C. Fougères, M. L. Avila, H. Jayatissa, D. Santiago-Gonzalez, K. Brandenburg, Z. Meisel, P. Mohr, F. Montes, C. Műller-Gatermann, D. Neto, W.-J. Ong, J. Pereira, K. E. Rehm, T. L. Tang, I. A. Tolstukhin, L. Varriano, G. Wilson, J. Wu
Feb 05 2024 nucl-ex arXiv:2402.01534v1

@misc{2402.01534, author = {C.~Fougères and M.~L.~Avila and H.~Jayatissa and D.~Santiago-Gonzalez and K.~Brandenburg and Z.~Meisel and P.~Mohr and F.~Montes and C.~Műller-Gatermann and D.~Neto and W.-J.~Ong and J.~Pereira and K.~E.~Rehm and T.~L.~Tang and I.~A.~Tolstukhin and L.~Varriano and G.~Wilson and J.~Wu}, title = {{D}irect cross-section measurement of the weak r-process 88{S}r(\alpha,n)91{Z}r reaction in \nu-driven winds of core collapse supernovae}, year = {2024}, eprint = {2402.01534}, note = {arXiv:2402.01534v1} }
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About half of the heavy elements beyond iron are known to be produced by the rapid neutron capture process, known as r-process. However, the astrophysical site producing the r-process is still uncertain. Chemical abundances observed in several cosmic sites indicate that different mechanisms should be at play. For instance, the abundances around silver measured in a subset of metal-poor stars indicate the presence of a weak r-process. This process may be active in neutrino-driven winds of core collapse supernovae where (${\alpha}$,n) reactions dominate the synthesis of Z ~ 40 elements in the expelled materials. Scarcely measured, the rates of (${\alpha}$,n) reactions are determined from statistical Hauser-Feshbach calculations with ${\alpha}$-optical-model potentials, which are still poorly constrained. The uncertainties of the (${\alpha}$,n) reaction rates therefore make a significant contribution to the uncertainties of the abundances determined from stellar modeling. In this work, the $^{88}$Sr(${\alpha}$,n)$^{91}$Zr reaction which impacts the weak r-process abundances has been probed at astrophysics energy for the first time; directly measuring the total cross sections at astrophysical energies of 8.37 - 13.09 MeV in the center of mass (3.8 - 7.5 GK). Two measurements were performed at ATLAS with the electrically-segmented ionization chamber MUSIC, in inverse kinematics, while following the active target technique. The cross sections of this ${\alpha}$-induced reaction on $^{88}$Sr, located at the shell closure N = 50, have been found to be lower than expected, by a factor of 3, despite recent statistical calculations validated by measurements on neighboring nuclei. This result encourages more experimental investigations of (${\alpha}$,n) reactions, at N = 50 and towards the neutron-rich side, to further test the predictive power and reliability of such calculations.
Precise Mass Measurements of $A=133$ Isobars with the Canadian Penning Trap: Resolving the $Q_{\beta^-}$ anomaly at $^{133}$Te
A.A. Valverde, F.G. Kondev, B. Liu, D. Ray, M. Brodeur, D.P. Burdette, N. Callahan, A. Cannon, J.A. Clark, D.E.M. Hoff, R. Orford, W.S. Porter, K.S. Sharma, L. Varriano
Dec 13 2023 nucl-ex arXiv:2312.06903v4

@misc{2312.06903, author = {A.A.~Valverde and F.G.~Kondev and B.~Liu and D.~Ray and M.~Brodeur and D.P.~Burdette and N.~Callahan and A.~Cannon and J.A.~Clark and D.E.M.~Hoff and R.~Orford and W.S.~Porter and K.S.~Sharma and L.~Varriano}, title = {{P}recise {M}ass {M}easurements of ${A}=133$ {I}sobars with the {C}anadian {P}enning {T}rap: {R}esolving the ${Q}_{\beta^-}$ anomaly at $^{133}${T}e}, year = {2023}, eprint = {2312.06903}, note = {arXiv:2312.06903v4} }
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We report precision mass measurements of $^{133}$Sb, $^{133g,m}$Te, and $^{133g,m}$I, produced at CARIBU at Argonne National Laboratory's ATLAS facility and measured using the Canadian Penning Trap mass spectrometer. These masses clarify an anomaly in the $^{133}$Te $\beta$-decay. The masses reported in the 2020 Atomic Mass Evaluation (M. Wang et al., 2021) produce $Q_{\beta^-}(^{133}$Te)=2920(6) keV; however, the highest-lying $^{133}$I level populated in this decay is observed at $E_i=2935.83(15)$ keV, resulting in an anomalous $Q_{\beta^{-}}^{i}=-16(6)$~keV. Our new measurements give $Q_{\beta^-}(^{133}\text{Te})=2934.8(11)$ keV, a factor of five more precise, yielding $Q{_\beta^i}=-1.0(12)$~keV, a 3$\sigma$ shift from the previous results. This resolves this anomaly, but indicates further anomalies in our understanding of the structure of this isotope.
The Beta-decay Paul Trap Mk IV: Design and commissioning
L. Varriano, G. Savard, J. A. Clark, D. P. Burdette, M. T. Burkey, A. T. Gallant, T. Y. Hirsh, B. Longfellow, N. D. Scielzo, R. Segel, E. J. Boron III, M. Brodeur, N. Callahan, A. Cannon, K. Kolos, B. Liu, S. Lopez-Caceres, M. Gott, B. Maaß, S. T. Marley, et al (12)
Nov 03 2023 physics.ins-det nucl-ex arXiv:2311.00723v1

@misc{2311.00723, author = {L.~Varriano and G.~Savard and J.~A.~Clark and D.~P.~Burdette and M.~T.~Burkey and A.~T.~Gallant and T.~Y.~Hirsh and B.~Longfellow and N.~D.~Scielzo and R.~Segel and E.~J.~Boron III and M.~Brodeur and N.~Callahan and A.~Cannon and K.~Kolos and B.~Liu and S.~Lopez-Caceres and M.~Gott and B.~Maaß and S.~T.~Marley and C.~Mohs and G.~E.~Morgan and P.~Mueller and M.~Oberling and P.~D.~O'Malley and W.~S.~Porter and Z.~Purcell and D.~Ray and F.~Rivero and A.~A.~Valverde and G.~L.~Wilson and R.~Zite}, title = {{T}he {B}eta-decay {P}aul {T}rap {M}k {IV}: {D}esign and commissioning}, year = {2023}, eprint = {2311.00723}, howpublished = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1058, 168818 (2024)}, doi = {10.1016/j.nima.2023.168818}, note = {arXiv:2311.00723v1} }
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The Beta-decay Paul Trap is an open-geometry, linear trap used to measure the decays of $^8$Li and $^8$B to search for a tensor contribution to the weak interaction. In the latest $^8$Li measurement of Burkey et al. (2022), $\beta$ scattering was the dominant experimental systematic uncertainty. The Beta-decay Paul Trap Mk IV reduces the prevalence of $\beta$ scattering by a factor of 4 through a redesigned electrode geometry and the use of glassy carbon and graphite as electrode materials. The trap has been constructed and successfully commissioned with $^8$Li in a new data campaign that collected 2.6 million triple coincidence events, an increase in statistics by 30% with 4 times less $\beta$ scattering compared to the previous $^8$Li data set.
Fundamental Symmetries, Neutrons, and Neutrinos (FSNN): Whitepaper for the 2023 NSAC Long Range Plan
B. Acharya, C. Adams, A.A. Aleksandrova, K. Alfonso, P. An, S. Baeßler, A.B. Balantekin, P.S. Barbeau, F. Bellini, V. Bellini, R.S. Beminiwattha, J.C. Bernauer, T. Bhattacharya, M. Bishof, A.E. Bolotnikov, P.A. Breur, M. Brodeur, J.P. Brodsky, L.J. Broussard, T. Brunner, et al (159)
Apr 10 2023 nucl-ex arXiv:2304.03451v1

@misc{2304.03451, author = {B.~Acharya and C.~Adams and A.A.~Aleksandrova and K.~Alfonso and P.~An and S.~Baeßler and A.B.~Balantekin and P.S.~Barbeau and F.~Bellini and V.~Bellini and R.S.~Beminiwattha and J.C.~Bernauer and T.~Bhattacharya and M.~Bishof and A.E.~Bolotnikov and P.A.~Breur and M.~Brodeur and J.P.~Brodsky and L.J.~Broussard and T.~Brunner and D.P.~Burdette and J.~Caylor and M.~Chiu and V.~Cirigliano and J.A.~Clark and S.M.~Clayton and T.V.~Daniels and L.~Darroch and Z.~Davoudi and A.~de Gouvêa and W.~Dekens and M.~Demarteau and D.~DeMille and A.~Deshpande and J.A.~Detwiler and G.W.~Dodson and M.J.~Dolinski and S.R.~Elliott and J.~Engel and J.~Erler and B.W.~Filippone and N.Fomin and J.A.~Formaggio and F.Q.L.~Friesen and J.Fry and B.K.~Fujikawa and G.~Fuller and K.~Fuyuto and A.~T.~Gallant and G.~Gallina and A.~Garcia Ruiz and R.~F.~Garcia Ruiz and S.~Gardner and F.~M.~Gonzalez and G.~Gratta and J.~Gruszko and V.~Gudkov and V.E.~Guiseppe and T.D.~Gutierrez and E.V.~Hansen and C.A.~Hardy and W.C.~Haxton and L.~Hayen and S.~Hedges and K.M.~Heeger and M.~Heffner and J.~Heise and R.~Henning and H.~Hergert and D.W.~Hertzog and D.~Hervas Aguilar and J.D.~Holt and S.F.~Hoogerheide and E.W.~Hoppe and M.~Horoi and C.R.~Howell and M.~Huang and N.R.~Hutzler and K.~Imam and T.M.~Ito and A.~Jamil and R.V.~Janssens and A.M.~Jayich and B.J.P.~Jones and P.~Kammel and K.F.~Liu and V.~Khachatryan and P.M.~King and J.R.~Klein and J.P.~Kneller and Yu.~G.~Kolomensky and W.~Korsch and R.~Krücken and K.S.~Kumar and K.D.~Launey and D.~Lawrence and K.G.~Leach and B.~Lehnert and B.G.~Lenardo and Z.~Li and H.-W.~Lin and B.~Longfellow and S.~Lopez-Caceres and C.~Lunardini and R.~MacLellan and D.M.~Markoff and R.H.~Maruyama and D.G.~Mathews and D.~Melconian and E.~Mereghetti and P.~Mohanmurthy and D.C.~Moore and P.E.~Mueller and H.P.~Mumm and W.~Nazarewicz and J.~Newby and A.N.~Nicholson and E.~Novitski and J.C.~Nzobadila Ondze and T.~O'Donnell and G.D.~Orebi Gann and J.L.~Orrell and J.L.~Ouellet and D.S.~Parno and K.D.~Paschke and S.~Pastore and R.W.~Pattie Jr and A.A.~Petrov and M.L.~Pitt and B.~Plaster and D.~Pocanic and A.~Pocar and A.W.P.~Poon and D.C.~Radford and H.~Rahangdale and B.C.~Rasco and H.~Rasiwala and R.P.~Redwine and A.~Ritz and L.~Rogers and G.~Ron and R.~Saldanha and S.~Sangiorgio and G.H.~Sargsyan and A.~Saunders and G.~Savard and D.C.~Schaper and K.~Scholberg and N.D.~Scielzo and C.-Y.~Seng and A.~Shindler and J.T.~Singh and M.~Singh and V.~Singh and W.M.~Snow and A.K.~Soma and P.A.~Souder and D.H.~Speller and J.~Stachurska and P.T.~Surukuchi and B.~Tapia Oregui and O.~Tomalak and J.A.~Torres and O.A.~Tyuka and B.A.~VanDevender and L.~Varriano and R.~Vogt and A.~Walker-Loud and K.~Wamba and S.L.~Watkins and F.E.~Wietfeldt and W.D.~Williams and J.T.~Wilson and L.~Winslow and X.L.~Yan and L.~Yang and A.R.~Young and X.~Zheng and Y.~Zhou}, title = {{F}undamental {S}ymmetries, {N}eutrons, and {N}eutrinos ({FSNN}): {W}hitepaper for the 2023 {NSAC} {L}ong {R}ange {P}lan}, year = {2023}, eprint = {2304.03451}, note = {arXiv:2304.03451v1} }
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This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail.
Improved Limit on Tensor Currents in the Weak Interaction from $^8$Li $\beta$ Decay
M. T. Burkey, G. Savard, A. T. Gallant, N. D. Scielzo, T. Y. Hirsh, L. Varriano, G. H. Sargsyan, K. D. Launey, M. Brodeur, D. P. Burdette, E. Heckmaier, K. Joerres, J. W. Klimes, K. Kolos, A. Laminack, K. G. Leach, A. F. Levand, B. Longfellow, B. Maaß, S. T. Marley, et al (11)
May 05 2022 nucl-ex hep-ph nucl-th arXiv:2205.01865v1

@misc{2205.01865, author = {M.~T.~Burkey and G.~Savard and A.~T.~Gallant and N.~D.~Scielzo and T.~Y.~Hirsh and L.~Varriano and G.~H.~Sargsyan and K.~D.~Launey and M.~Brodeur and D.~P.~Burdette and E.~Heckmaier and K.~Joerres and J.~W.~Klimes and K.~Kolos and A.~Laminack and K.~G.~Leach and A.~F.~Levand and B.~Longfellow and B.~Maaß and S.~T.~Marley and G.~E.~Morgan and P.~Mueller and R.~Orford and S.~W.~Padgett and A.~Pérez Galván and J.~R.~Pierce and D.~Ray and R.~Segel and K.~Siegl and K.~S.~Sharma and B.~S.~Wang}, title = {{I}mproved {L}imit on {T}ensor {C}urrents in the {W}eak {I}nteraction from $^8${L}i $\beta$ {D}ecay}, year = {2022}, eprint = {2205.01865}, note = {arXiv:2205.01865v1} }
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The electroweak interaction in the Standard Model (SM) is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this work, we present the most precise measurement of tensor currents in the low-energy regime by examining the $\beta$-$\bar{\nu}$ correlation of trapped $^{8}$Li ions with the Beta-decay Paul Trap. We find $a_{\beta\nu} = -0.3325 \pm 0.0013_{stat} \pm 0.0019_{syst}$ at $1\sigma$ for the case of coupling to right-handed neutrinos $(C_T=-C_T')$, which is consistent with the SM prediction.
Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly
L. J. Broussard, J. L. Barrow, L. DeBeer-Schmitt, T. Dennis, M. R. Fitzsimmons, M. J. Frost, C. E. Gilbert, F. M. Gonzalez, L. Heilbronn, E. B. Iverson, A. Johnston, Y. Kamyshkov, M. Kline, P. Lewiz, C. Matteson, J. Ternullo, L. Varriano, S. Vavra
Nov 11 2021 nucl-ex hep-ex arXiv:2111.05543v2

@misc{2111.05543, author = {L.~J.~Broussard and J.~L.~Barrow and L.~DeBeer-Schmitt and T.~Dennis and M.~R.~Fitzsimmons and M.~J.~Frost and C.~E.~Gilbert and F.~M.~Gonzalez and L.~Heilbronn and E.~B.~Iverson and A.~Johnston and Y.~Kamyshkov and M.~Kline and P.~Lewiz and C.~Matteson and J.~Ternullo and L.~Varriano and S.~Vavra}, title = {{E}xperimental {S}earch for {N}eutron to {M}irror {N}eutron {O}scillations as an {E}xplanation of the {N}eutron {L}ifetime {A}nomaly}, year = {2021}, eprint = {2111.05543}, note = {arXiv:2111.05543v2} }
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An unexplained $>4\,\sigma$ discrepancy persists between "beam" and "bottle" measurements of the neutron lifetime. A new model proposed that conversions of neutrons $n$ into mirror neutrons $n'$, part of a dark mirror sector, can increase the apparent neutron lifetime by $1\%$ via a small mass splitting $\Delta{m}$ between $n$ and $n'$ inside the 4.6 T magnetic field of the National Institute of Standards and Technology Beam Lifetime experiment. A search for neutron conversions in a 6.6 T magnetic field was performed at the Spallation Neutron Source which excludes this explanation for the neutron lifetime discrepancy.
Neutron-Mirror Neutron oscillations in Matter
Yuri Kamyshkov, James Ternullo, Louis Varriano, Zurab Berezhiani
Nov 04 2021 hep-ph nucl-ex nucl-th arXiv:2111.01791v1

@misc{2111.01791, author = {Yuri Kamyshkov and James Ternullo and Louis Varriano and Zurab Berezhiani}, title = {{N}eutron-{M}irror {N}eutron oscillations in {M}atter}, year = {2021}, eprint = {2111.01791}, note = {arXiv:2111.01791v1} }
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The possibility that a neutron can be transformed to a hidden sector particle remains intriguingly open. Proposed theoretical models conjecture that the hidden sector can be represented by a mirror sector, and the neutron n can oscillate into its sterile mirror twin n', exactly or nearly degenerate in mass with n. Oscillations n - n' can take place in vacuum and in the environment of the regular matter and the magnetic field where only neutron will be subject of interaction with the environment. We describe the propagation of the oscillating n - n' system as a particle of the cold neutron beam passing through the dense absorbing materials in connection with the possible regeneration type of experiments where the effect of n -> n' -> n transformation can be observed.
Impact of clustering on the $^8$Li $\beta$ decay and recoil form factors
G. H. Sargsyan, K. D. Launey, M. T. Burkey, A. T. Gallant, N. D. Scielzo, G. Savard, A. Mercenne, T. Dytrych, D. Langr, L. Varriano, B. Longfellow, T. Y. Hirsh, J. P. Draayer
Jul 23 2021 nucl-th nucl-ex arXiv:2107.10389v2

@misc{2107.10389, author = {G.~H.~Sargsyan and K.~D.~Launey and M.~T.~Burkey and A.~T.~Gallant and N.~D.~Scielzo and G.~Savard and A.~Mercenne and T.~Dytrych and D.~Langr and L.~Varriano and B.~Longfellow and T.~Y.~Hirsh and J.~P.~Draayer}, title = {{I}mpact of clustering on the $^8${L}i $\beta$ decay and recoil form factors}, year = {2021}, eprint = {2107.10389}, howpublished = {Phys. Rev. Lett. 128, 202503 (2022)}, doi = {10.1103/PhysRevLett.128.202503}, note = {arXiv:2107.10389v2} }
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We place unprecedented constraints on recoil corrections in the $\beta$ decay of $^8$Li, by identifying a strong correlation between them and the $^8$Li ground state quadrupole moment in large-scale ab initio calculations. The results are essential for improving the sensitivity of high-precision experiments that probe the weak interaction theory and test physics beyond the Standard Model (BSM). In addition, our calculations predict a $2^+$ state of the $\alpha+\alpha$ system that is energetically accessible to $\beta$ decay but has not been observed in the experimental $^8$Be energy spectrum, and has an important effect on the recoil corrections and $\beta$ decay for the $A=8$ systems. This state and an associated $0^+$ state are notoriously difficult to model due to their cluster structure and collective correlations, but become feasible for calculations in the ab initio symmetry-adapted no-core shell-model framework.
On the Neutron Transition Magnetic Moment
Zurab Berezhiani, Riccardo Biondi, Yuri Kamyshkov, Louis Varriano
Dec 31 2018 nucl-th nucl-ex arXiv:1812.11141v2

@misc{1812.11141, author = {Zurab Berezhiani and Riccardo Biondi and Yuri Kamyshkov and Louis Varriano}, title = {{O}n the {N}eutron {T}ransition {M}agnetic {M}oment}, year = {2018}, eprint = {1812.11141}, howpublished = {Physics 2019, 1(2), 271-289}, doi = {10.3390/physics1020021}, note = {arXiv:1812.11141v2} }
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We discuss the possibility of the transition magnetic moments (TMM) between the neutron n and mirror neutron n', its hypothetical sterile twin from parallel particle "mirror" sector. The neutron can be spontaneously converted into mirror neutron via these TMM's (in addition to the more conventional transition channel due to n-n' mass mixing) interacting with the magnetic field B as well as with mirror magnetic field B'. We derive analytic formula for the average probability of n-n' oscillation and consider possible manifestations of the neutron TMM effects. In particular, we discuss potential role of these effects in the neutron lifetime measurement experiments leading us to new, testable predictions.
New Search for Mirror Neutrons at HFIR
L. J. Broussard, K. M. Bailey, W. B. Bailey, J. L. Barrow, B. Chance, C. Crawford, L. Crow, L. DeBeer-Schmitt, N. Fomin, M. Frost, A. Galindo-Uribarri, F. X. Gallmeier, L. Heilbronn, E. B. Iverson, Y. Kamyshkov, C.-Y. Liu, I. Novikov, S. I. Pentillä, A. Ruggles, B. Rybolt, et al (5)
Oct 03 2017 hep-ex nucl-ex physics.ins-det arXiv:1710.00767v2

@misc{1710.00767, author = {L.~J.~Broussard and K.~M.~Bailey and W.~B.~Bailey and J.~L.~Barrow and B.~Chance and C.~Crawford and L.~Crow and L.~DeBeer-Schmitt and N.~Fomin and M.~Frost and A.~Galindo-Uribarri and F.~X.~Gallmeier and L.~Heilbronn and E.~B.~Iverson and Y.~Kamyshkov and C.-Y.~Liu and I.~Novikov and S.~I.~Pentillä and A.~Ruggles and B.~Rybolt and M.~Snow and L.~Townsend and L.~J.~Varriano and S.~Vavra and A.~R.~Young}, title = {{N}ew {S}earch for {M}irror {N}eutrons at {HFIR}}, year = {2017}, eprint = {1710.00767}, note = {arXiv:1710.00767v2} }
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The theory of mirror matter predicts a hidden sector made up of a copy of the Standard Model particles and interactions but with opposite parity. If mirror matter interacts with ordinary matter, there could be experimentally accessible implications in the form of neutral particle oscillations. Direct searches for neutron oscillations into mirror neutrons in a controlled magnetic field have previously been performed using ultracold neutrons in storage/disappearance measurements, with some inconclusive results consistent with characteristic oscillation time of $\tau$$\sim$10~s. Here we describe a proposed disappearance and regeneration experiment in which the neutron oscillates to and from a mirror neutron state. An experiment performed using the existing General Purpose-Small Angle Neutron Scattering instrument at the High Flux Isotope Reactor at Oak Ridge National Laboratory could have the sensitivity to exclude up to $\tau$$<$15~s in 1 week of beamtime and at low cost.