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Search Results: 1 - 10 of 191403 matches for " D. Howdle "
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Evidence for the involvement of NOD2 in regulating colonic epithelial cell growth and survival
Sheena M Cruickshank, Louise Wakenshaw, John Cardone, Peter D Howdle, Peter J Murray, Simon R Carding
World Journal of Gastroenterology , 2008,
Abstract: AIM: To investigate the function of NOD2 in colonic epithelial cells (CEC).METHODS: A combination of in vivo and in vitro analyses of epithelial cell turnover in the presence and absence of a functional NOD2 protein and, in response to enteric Salmonella typhimurium infection, were used. shRNA interference was also used to investigate the consequences of knocking down NOD2 gene expression on the growth and survival of colorectal carcinoma cell lines.RESULTS: In the colonic mucosa the highest levels of NOD2 expression were in proliferating crypt epithelial cells. Muramyl dipeptide (MDP), that is recognized by NOD2, promoted CEC growth in vitro. By contrast, the growth of NOD2-deficient CECs was impaired. In vivo CEC proliferation was also reduced and apoptosis increased in Nod2-/- mice, which were also evident following enteric Salmonella infection. Furthermore, neutralization of NOD2 mRNA expression in human colonic carcinoma cells by shRNA interference resulted in decreased survival due to increased levels of apoptosis.CONCLUSION: These findings are consistent with the involvement of NOD2 protein in promoting CEC growth and survival. Defects in proliferation by CECs in cases of CD may contribute to the underlying pathology of disrupted intestinal homeostasis and excessive inflammation.
First measurement of target and beam-target asymmetries in the $γ p\to π^0ηp$ reaction
J. R. M. Annand,H. J. Arends,R. Beck,N. Borisov,A. Braghieri,W. J. Briscoe,S. Cherepnya,C. Collicott,S. Costanza,E. J. Downie,M. Dieterle,A. Fix,L. V. Fil'kov,S. Garni,D. I. Glazier,W. Gradl,G. Gurevich,P. H. Barrientos,D. Hamilton,D. Hornidge,D. Howdle,G. M. Huber,V. L. Kashevarov,I. Keshelashvili,R. Kondratiev,M. Korolija,B. Krusche,A. Lazarev,V. Lisin,K. Livingston,I. J. D. MacGregor,J. Mancel,D. M. Manley,P. Martel,E. F. McNicoll,W. Meyer,D. Middleton,R. Miskimen,A. Mushkarenkov,A. Neganov,A. Nikolaev,M. Oberle,H. Ortega,M. Ostrick,P. Ott,P. B. Otte,B. Oussena,P. Pedroni,A. Polonski,V. V. Polyanski,S. Prakhov,G. Reicherz,T. Rostomyan,A. Sarty,S. Schumann,O. Steffen,I. I. Strakovsky,T. Strub,I. Supek,L. Tiator,A. Thomas,M. Unverzagt,Y. A. Usov,D. P. Watts,D. Werthmüller,L. Witthauer,M. Wolfes
Physics , 2015, DOI: 10.1103/PhysRevC.91.055208
Abstract: The first data on target and beam-target asymmetries for the $\gamma p\to\pi^0\eta p$ reaction at photon energies from 1050 up to 1450 MeV are presented. The measurements were performed using the Crystal Ball and TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The general assumption that the reaction is dominated by the $\Delta 3/2^-$ amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves.
Photoproduction of pi0-mesons off neutrons in the nucleon resonance region
M. Dieterle,I. Keshelashvili,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,P. A. Bartolome,R. Beck,V. Bekrenev,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,B. Demissie,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,I. Jaegle,O. Jahn,T. C. Jude,A. Kaeser,V. L. Kashevarov,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,A. Kulbardis,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. McNicoll,D. Mekterovic,V. Metag,S. Micanovic,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts,D. Werthmueller,L. Witthauer
Physics , 2014, DOI: 10.1103/PhysRevLett.112.142001
Abstract: Precise angular distributions have been measured for the first time for the photoproduction of $\pi^{0}$-mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasi-free protons bound in the deuteron to the results for free protons and then applied as a correction to the quasi-free neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between $0.45$~GeV and $1.4$~GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.
Photoproduction of $π^0$-pairs off protons and off neutrons
M. Dieterle,M. Oberle,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,P. A. Bartolome,R. Beck,V. Bekrenev,H. Bergh?user,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,S. Costanza,B. Demissie,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,S. Garni,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,O. Jahn,T. C. Jude,A. K?ser,V. L. Kashevarov,I. Keshelashvili,R. Kondratiev,M. Korolija,B. Krusche,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,J. C. McGeorge,E. McNicoll,D. Mekterovic,V. Metag,S. Micanovic,D. G. Middleton,A. Mushkarenkov,A. Nikolaev,R. Novotny,M. Ostrick,P. Otte,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. Prakhov,J. Robinson,T. Rostomyan,S. Schumann,M. H. Sikora,D. I. Sober,A. Starostin,Th. Strub,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,N. K. Walford,D. P. Watts,D. Werthmüller,L. Witthauer
Physics , 2015,
Abstract: Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $\pi^0\pi^0$ pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400~MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15\%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final state invariant masses up to $\approx$1550~MeV), where both reactions are dominated by the $N(1520)3/2^-\rightarrow \Delta(1232)3/2^+\pi$ decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an $N^{\star}\rightarrow N\sigma$ decay for the proton, while the reaction is dominated by a sequential decay via a $\Delta\pi$ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled channel analysis.
The isospin structure of photoproduction of pi-eta pairs from the nucleon in the threshold region
A. K?ser,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,P. A. Bartolome,R. Beck,V. Bekrenev,H. Bergh?user,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,S. Costanza,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,O. Jahn,I. Jaegle,T. C. Jude,V. L. Kashevarov,I. Keshelashvili,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,J. C. McGeorge,E. McNicoll,D. Mekterovic,V. Metag,S. Micanovic,D. G. Middleton,A. Mushkarenkov,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,P. Otte,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. I. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts,D. Werthmüller,L. Witthauer
Physics , 2015,
Abstract: Photoproduction of $\pi\eta$-pairs from nucleons has been investigated from threshold up to incident photon energies of $\approx$~1.4~GeV. The quasi-free reactions $\gamma p\rightarrow p\pi^0\eta$, $\gamma n\rightarrow n\pi^0\eta$, $\gamma p\rightarrow n\pi^+\eta$, and $\gamma n\rightarrow p\pi^-\eta$ were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the $\gamma p\rightarrow n\pi^+\eta$ reaction was measured for the first time). For the $\pi^0\eta$ final state coherent production via the $\gamma d\rightarrow d\pi^0\eta$ reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost $4\pi$ coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four different final states obey the relation $\sigma(p\pi^0\eta)$ $\approx$ $\sigma(n\pi^0\eta)$ $\approx$ $2\sigma(p\pi^-\eta)$ $\approx$ $2\sigma(n\pi^+\eta)$ as expected for a dominant contribution from a $\Delta^{\star}\rightarrow\eta\Delta(1232)\rightarrow\pi\eta N$ reaction chain, which is also supported by the shapes of the invariant-mass distributions of nucleon-meson and $\pi$-$\eta$ pairs. The experimental results are compared to the predictions from an isobar reaction model.
Quasi-free photoproduction of eta-mesons off 3He nuclei
L. Witthauer,D. Werthmueller,I. Keshelashvili,P. Aguar-Bartolome,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,R. Beck,V. Bekrenev,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,I. Jaegle,O. Jahn,T. C. Jude,A. Kaeser,V. L. Kashevarov,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,A. Kulbardis,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. McNicoll,V. Metag,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. Prakhov,J. Robinson,G. Rosner,M. Rost,T. Rostomyan,S. Schumann,M. H. Sikora,D. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts
Physics , 2013, DOI: 10.1140/epja/i2013-13154-0
Abstract: Quasi-free photoproduction of $\eta$-mesons has been measured off nucleons bound in $^3$He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost $4\pi$ covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The $\eta$-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the $S_{11}$(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron results. On an absolute scale the cross sections for both quasi-free protons and neutrons are suppressed with respect to the deuteron target pointing to significant nuclear final state interaction effects.
Measurement of the beam-helicity asymmetry $I^{\odot}$ in the photoproduction of $π^0π^{\pm}$-pairs off protons and off neutrons
M. Oberle,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,P. A. Bartolome,R. Beck,V. Bekrenev,H. Berghaeuser,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,O. Jahn,I. Jaegle,T. C. Jude,A. Kaeser,V. L. Kashevarov,I. Keshelashvili,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,A. Kulbardis,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. McNicoll,D. Mekterovic,V. Metag,S. Micanovic,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Ostrick,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. I. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts,D. Werthmueller,L. Witthauer,F. Zehr
Physics , 2014, DOI: 10.1140/epja/i2014-14054-5
Abstract: Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions $\boldsymbol{\gamma}p\rightarrow n\pi^0\pi^+$ off free protons and $\boldsymbol{\gamma}d\rightarrow (p)p\pi^0\pi^-$ and $\boldsymbol{\gamma}d\rightarrow (n)n\pi^0\pi^+$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. The charged pions, recoil protons, recoil neutrons, and decay photons from $\pi^0$ mesons were detected in the 4$\pi$ electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. Using a complete kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons, suggesting that the quasi-free neutron results are also a close approximation of the free-neutron asymmetries. A comparison of the results to the predictions of the Two-Pion-MAID reaction model shows that the reaction mechanisms are still not well understood, in particular at low incident photon energies in the second nucleon-resonance region.
Quasifree photoproduction of $η$ mesons off protons and neutrons
A2 Collaboration,D. Werthmüller,L. Witthauer,I. Keshelashvili,P. Aguar-Bartolomé,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,R. Beck,V. Bekrenev,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,S. Costanza,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,I. Jaegle,O. Jahn,T. C. Jude,A. K?ser,V. L. Kashevarov,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,A. Kulbardis,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. F. McNicoll,V. Metag,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,P. B. Otte,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts
Physics , 2014, DOI: 10.1103/PhysRevC.90.015205
Abstract: Differential and total cross sections for the quasifree reactions $\gamma p\rightarrow\eta p$ and $\gamma n\rightarrow\eta n$ have been determined at the MAMI-C electron accelerator using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy-tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0 \rightarrow 6\gamma$ and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The $\eta$-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the $S_{11}(1535)$ resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy $W = (1670\pm 5)$ MeV with an intrinsic width of $\Gamma\approx 30$ MeV.
Coherent photoproduction of eta-mesons off 3He - search for eta-mesic nuclei
F. Pheron,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,P. A. Bartolome,R. Beck,V. Bekrenev,H. Berghaeuser,B. Boillat,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,D. I. Glazier,E. Heid,L. V. Fil'kov,D. Hornidge,D. Howdle,O. Jahn,I. Jaegle,T. C. Jude,V. L. Kashevarov,I. Keshelashvili,R. Kondratiev,M. Korolija,M. Kotulla,A. Kulbardis,S. P. Kruglov,B. Krusche,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. McNicoll,D. Mekterovic,V. Metag,S. Micanovic,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,B. Oussena,P. Pedroni,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. I. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts,D. Werthmueller,L. Witthauer,F. Zehr
Physics , 2012, DOI: 10.1016/j.physletb.2012.01.075
Abstract: Coherent photoproduction of $\eta$-mesons off $^3$He, i.e. the reaction $\gamma ^3{He}\rightarrow \eta ^3{He}$, has been investigated in the near-threshold region. The experiment was performed at the Glasgow tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball - TAPS detector. Angular distributions and the total cross section were measured using the $\eta\rightarrow \gamma\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ decay channels. The observed extremely sharp rise of the cross section at threshold and the behavior of the angular distributions are evidence for a strong $\eta {^3{He}}$ final state interaction, pointing to the existence of a resonant state. The search for further evidence of this state in the excitation function of $\pi^0$-proton back-to-back emission in the $\gamma ^3{He}\rightarrow \pi^0 pX$ reaction revealed a very complicated structure of the background and could not support previous conclusions.
A narrow structure in the excitation function of eta-photoproduction off the neutron
D. Werthmueller,L. Witthauer,I. Keshelashvili,P. Aguar-Bartolome,J. Ahrens,J. R. M. Annand,H. J. Arends,K. Bantawa,R. Beck,V. Bekrenev,A. Braghieri,D. Branford,W. J. Briscoe,J. Brudvik,S. Cherepnya,B. Demissie,M. Dieterle,E. J. Downie,P. Drexler,L. V. Fil'kov,A. Fix,D. I. Glazier,D. Hamilton,E. Heid,D. Hornidge,D. Howdle,G. M. Huber,I. Jaegle,O. Jahn,T. C. Jude,A. Kaeser,V. L. Kashevarov,R. Kondratiev,M. Korolija,S. P. Kruglov,B. Krusche,A. Kulbardis,V. Lisin,K. Livingston,I. J. D. MacGregor,Y. Maghrbi,J. Mancell,D. M. Manley,Z. Marinides,M. Martinez,J. C. McGeorge,E. F. McNicoll,V. Metag,D. G. Middleton,A. Mushkarenkov,B. M. K. Nefkens,A. Nikolaev,R. Novotny,M. Oberle,M. Ostrick,B. Oussena,P. Pedroni,F. Pheron,A. Polonski,S. N. Prakhov,J. Robinson,G. Rosner,T. Rostomyan,S. Schumann,M. H. Sikora,D. Sober,A. Starostin,I. Supek,M. Thiel,A. Thomas,M. Unverzagt,D. P. Watts
Physics , 2013, DOI: 10.1103/PhysRevLett.111.232001
Abstract: The photoproduction of $\eta$-mesons off nucleons bound in $^2$H and $^3$He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0$ decays and the recoil nucleons were detected with an almost $4\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\gamma n\rightarrow n\eta$. The results from the two measurements are consistent taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W$ = (1670$\pm$5) MeV and $\Gamma$ =(30$\pm$15) MeV. For the first time precise results for the angular dependence of this structure have been extracted.
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