| Home | << 1 2 3 4 5 6 7 >> |
|
| Records | |||||
|---|---|---|---|---|---|
| Author | Gerecht, E.; Musante, C. F.; Zhuang, Y.; Yngvesson, K. S.; Gol’tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. | ||||
| Title | NbN hot electron bolometric mixerss—a new technology for low-noise THz receivers | Type | Journal Article | ||
| Year | 1999 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
Volume  |
47 | Issue | 12 | Pages | 2519-2527 |
| Keywords | NbN HEB mixers | ||||
| Abstract | New advances in hot electron bolometer (HEB) mixers have recently resulted in record-low receiver noise temperatures at terahertz frequencies. We have developed quasi-optically coupled NbN HEB mixers and measured noise temperatures up to 2.24 THz, as described in this paper. We project the anticipated future performance of such receivers to have even lower noise temperature and local-oscillator power requirement as well as wider gain and noise bandwidths. We introduce a proposal for integrated focal plane arrays of HEB mixers that will further increase the detection speed of terahertz systems. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1557-9670 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1560 | |||
| Permanent link to this record | |||||
| Author | Hans Ekstrom; Karasik, Boris S.; Kollberg, Erik L.; Sigfrid Yngvesson | ||||
| Title | Conversion gain and noise of niobium superconducting hot–electron–mixers | Type | Journal Article | ||
| Year | 1995 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | |
| Volume |
43 | Issue | 4 | Pages | 938-947 |
| Keywords | Nb HEB mixers | ||||
| Abstract | |||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 254 | |||
| Permanent link to this record | |||||
| Author | Zolotov, P. I.; Semenov, A. V.; Divochiy, A. V.; Goltsman, G. N.; Romanov, N. R.; Klapwijk, T. M. | ||||
| Title | Dependence of photon detection efficiency on normal-state sheet resistance in marginally superconducting films of NbN | Type | Journal Article | ||
| Year | 2021 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
31 | Issue | 5 | Pages | 1-5 |
| Keywords | NbN SSPD, SNSPD | ||||
| Abstract | We present an extensive set of data on nanowire-type superconducting single-photon detectors based on niobium-nitride (NbN) to establish the empirical correlation between performance and the normal-state resistance per square. We focus, in particular, on the bias current, compared to the expected depairing current, needed to achieve a near-unity detection efficiency for photon detection. The data are discussed within the context of a model in which the photon energy triggers the movement of vortices i.e. superconducting dissipation, followed by thermal runaway. Since the model is based on the non-equilibrium theory for conventional superconductors deviations may occur, because the efficient regime is found when NbN acts as a marginal superconductor in which long-range phase coherence is frustrated. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1222 | |||
| Permanent link to this record | |||||
| Author | Zolotov, P.; Semenov, A.; Divochiy, A.; Goltsman, G. | ||||
| Title | A comparison of VN and NbN thin films towards optimal SNSPD efficiency | Type | Journal Article | ||
| Year | 2021 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
31 | Issue | 5 | Pages | 1-4 |
| Keywords | NbN SSPD, SNSPD, WSi | ||||
| Abstract | Based on early phenomenological ideas about the operation of superconducting single-photon detectors (SSPD or SNSPD), it was expected that materials with a lower superconducting gap should perform better in the IR range. The plausibility of this concept could be checked using two popular SSPD materials – NbN and WSi films. However, these materials differ strongly in crystallographic structure (polycrystalline B1 versus amorphous), which makes their dependence on disorder different. In our work we present a study of the single-photon response of SSPDs made from two disordered B1 structure superconductors – vanadium nitride and niobium nitride thin films. We compare the intrinsic efficiency of devices made from films with different sheet resistance values. While both materials have a polycrystalline structure and comparable diffusion coefficient values, VN films show metallic behavior over a wide range of sheet resistance, in contrast to NbN films with an insulator-like temperature dependence of resistivity, which may be partially due to enhanced Coulomb interaction, leading to different starting points for the normal electron density of states. The results show that even though VN devices are more promising in terms of theoretical predictions, their optimal performance was not reached due to lower values of sheet resistance. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1223 | |||
| Permanent link to this record | |||||
| Author | Samsonova, A. S.; Zolotov, P. I.; Baeva, E. M.; Lomakin, A. I.; Titova, N. A.; Kardakova, A. I.; Goltsman, G. N. | ||||
| Title | Signatures of surface magnetic disorder in niobium films | Type | Journal Article | ||
| Year | 2021 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
31 | Issue | 5 | Pages | 1-5 |
| Keywords | Nb films | ||||
| Abstract | We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder ( kFl≈150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm −2 , which is in agreement with the previously reported data for Nb films. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1792 | |||
| Permanent link to this record | |||||
| Author | Smirnov, K.; Moshkova, M.; Antipov, A.; Morozov, P.; Vakhtomin, Y. | ||||
| Title | The cascade switching of the photon number resolving superconducting single-photon detectors | Type | Journal Article | ||
| Year | 2021 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
31 | Issue | 2 | Pages | 1-4 |
| Keywords | PNR SSPD, SNSPD | ||||
| Abstract | In this article, present the first detailed study of cascade switching in superconducting photon number resolving detectors. The detectors were made in the form of four parallel nanowires, coupled with the single-mode optical fiber and mounted into a closed-cycle refrigerator with a temperature of 2.1 K. We found out the value of additional false pulses (N cas.sw. ) appearing due to cascade switching and showed that it is possible to set up the detector bias current that corresponds to a high level of the detection efficiency and a low level of N cas.sw. simultaneously. We reached the detection efficiency of 60% and N cas.sw. = 0.3%. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1796 | |||
| Permanent link to this record | |||||
| Author | Polyakova, M.; Semenov, A. V.; Kovalyuk, V.; Ferrari, S.; Pernice, W. H. P.; Gol'tsman, G. N. | ||||
| Title | Protocol of measuring hot-spot correlation length for SNSPDs with near-unity detection efficiency | Type | Journal Article | ||
| Year | 2019 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
29 | Issue | 5 | Pages | 1-5 |
| Keywords | SSPD, waveguide-integrated SNSPD, hot-spot interaction length | ||||
| Abstract | We present a simple quantum detector tomography protocol, which allows, without ambiguities, to measure the two-spot detection efficiency and extract the hot-spot interaction length of superconducting nanowire single photon detectors (SNSPDs) with unity intrinsic detection efficiency. We identify a significant parasitic contribution to the measured two-spot efficiency, related to an effect of the bias circuit, and find a way to rule out this contribution during data post-processing and directly in the experiment. From the data analysis for waveguide-integrated SNSPD, we find signatures of the saturation of the two-spot efficiency and hot-spot interaction length of order of 100 nm. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1187 | |||
| Permanent link to this record | |||||
| Author | Korneev, A.; Korneeva, Y.; Florya, I.; Semenov, A.; Goltsman, G. | ||||
| Title | Photon switching statistics in multistrip superconducting single-photon detectors | Type | Journal Article | ||
| Year | 2018 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
28 | Issue | 7 | Pages | 1-4 |
| Keywords | SSPD, SNSPD | ||||
| Abstract | We study photon count statistics in superconducting single-photon detectors consisting of up to 70 narrow superconducting strips connected in parallel. Using interarrival time analysis, we demonstrate that our samples are operated in the “arm-trigger” regime and require up to seven subsequently absorbed photons to form a resistive state in the whole sample. We also performed numerical simulation of the light and dark count rates versus detector bias current, which are in good agreement with the experimental results. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1304 | |||
| Permanent link to this record | |||||
| Author | Lobanov, Y.; Shcherbatenko, M.; Semenov, A.; Kovalyuk, V.; Kahl, O.; Ferrari, S.; Korneev, A.; Ozhegov, R.; Kaurova, N.; Voronov, B. M.; Pernice, W. H. P.; Gol'tsman, G. N. | ||||
| Title | Superconducting nanowire single photon detector for coherent detection of weak signals | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 1-5 |
| Keywords | NbN SSPD mixer, SNSPD, nanophotonic waveguide | ||||
| Abstract | Traditional photon detectors are operated in the direct detection mode, counting incident photons with a known quantum efficiency. Here, we have investigated a superconducting nanowire single photon detector (SNSPD) operated as a photon counting mixer at telecommunication wavelength around 1.5 μm. This regime of operation combines excellent sensitivity of a photon counting detector with excellent spectral resolution given by the heterodyne technique. Advantageously, we have found that low local oscillator (LO) power of the order of hundreds of femtowatts to a few picowatts is sufficient for clear observation of the incident test signal with the sensitivity approaching the quantum limit. With further optimization, the required LO power could be significantly reduced, which is promising for many practical applications, such as the development of receiver matrices or recording ultralow signals at a level of less-than-one-photon per second. In addition to a traditional NbN-based SNSPD operated with normal incidence coupling, we also use detectors with a travelling wave geometry, where a NbN nanowire is placed on the top of a Si 3 N 4 nanophotonic waveguide. This approach is fully scalable and a large number of devices could be integrated on a single chip. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1206 | |||
| Permanent link to this record | |||||
| Author | Trifonov, A.; Tong, C.-Y. E.; Grimes, P.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. | ||||
| Title | Development of A Silicon Membrane-based Multi-pixel Hot Electron Bolometer Receiver | Type | Conference Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 6 |
| Keywords | Multi-pixel, HEB, silicon-on-insulator, horn array | ||||
| Abstract | We report on the development of a multi-pixel Hot Electron Bolometer (HEB) receiver fabricated using silicon membrane technology. The receiver comprises a 2 × 2 array of four HEB mixers, fabricated on a single chip. The HEB mixer chip is based on a superconducting NbN thin film deposited on top of the silicon-on-insulator (SOI) substrate. The thicknesses of the device layer and handling layer of the SOI substrate are 20 μm and 300 μm respectively. The thickness of the device layer is chosen such that it corresponds to a quarter-wave in silicon at 1.35 THz. The HEB mixer is integrated with a bow-tie antenna structure, in turn designed for coupling to a circular waveguide, |
||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | RPLAB @ kovalyuk @ | Serial | 1111 | ||
| Permanent link to this record | |||||
| Author | Titova, N.; Kardakova, A. I.; Tovpeko, N.; Ryabchun, S.; Mandal, S.; Morozov, D.; Klemencic, G. M.; Giblin, S. R.; Williams, O. A.; Goltsman, G. N.; Klapwijk, T. M. | ||||
| Title | Slow electron–phonon cooling in superconducting diamond films | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 1-4 |
| Keywords | superconducting diamond films, electron-phonon cooling | ||||
| Abstract | We have measured the electron-phonon energy-relaxation time, τ eph , in superconducting boron-doped diamond films grown on silicon substrate by chemical vapor deposition. The observed electron-phonon cooling times vary from 160 ns at 2.70 K to 410 ns at 1.8 K following a T -2-dependence. The data are consistent with the values of τ eph previously reported for single-crystal boron-doped diamond films epitaxially grown on diamond substrate. Such a noticeable slow electron-phonon relaxation in boron-doped diamond, in combination with a high normal-state resistivity, confirms a potential of superconducting diamond for ultrasensitive superconducting bolometers. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1168 | |||
| Permanent link to this record | |||||
| Author | Trifonov, A.; Tong, C.-Y. E.; Grimes, P.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. | ||||
| Title | Development of a silicon membrane-based multipixel hot electron bolometer receiver | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 1-5 |
| Keywords | Multi-pixel, NbN HEB, silicon-on-insulator, horn array | ||||
| Abstract | We report on the development of a multipixel hot electron bolometer (HEB) receiver fabricated using silicon membrane technology. The receiver comprises a 2 × 2 array of four HEB mixers, fabricated on a single chip. The HEB mixer chip is based on a superconducting NbN thin-film deposited on top of the silicon-on-insulator (SOI) substrate. The thicknesses of the device layer and handling layer of the SOI substrate are 20 and 300 μm, respectively. The thickness of the device layer is chosen such that it corresponds to a quarter-wave in silicon at 1.35 THz. The HEB mixer is integrated with a bow-tie antenna structure, in turn designed for coupling to a circular waveguide, fed by a monolithic drilled smooth-walled horn array. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1324 | |||
| Permanent link to this record | |||||
| Author | Korneeva, Y.; Florya, I.; Vdovichev, S.; Moshkova, M.; Simonov, N.; Kaurova, N.; Korneev, A.; Goltsman, G. | ||||
| Title | Comparison of hot spot formation in nbn and mon thin superconducting films after photon absorption | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 1-4 |
| Keywords | MoNx SSPD | ||||
| Abstract | In superconducting single-photon detectors (SSPD), the efficiency of local suppression of superconductivity and hotspot formation is controlled by diffusivity and electron-phonon interaction time. Here, we selected a material, 3.6-nm-thick MoNx film, which features diffusivity close to those of NbN traditionally used for SSPD fabrication, but with electron-phonon interaction time an order of magnitude larger. In MoN ∞ detectors, we study the dependence of detection efficiency on bias current, photon energy, and strip width, and compare it with NbN SSPD. We observe nonlinear current-energy dependence in MoNx SSPD and more pronounced plateaus in dependences of detection efficiency on bias current, which we attribute to longer electron-phonon interaction time. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1325 | |||
| Permanent link to this record | |||||
| Author | Trifonov, A.; Tong, C.-Y. E.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. | ||||
| Title | Photon absorption near the gap frequency in a hot electron bolometer | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
27 | Issue | 4 | Pages | 1-4 |
| Keywords | NBN HEB mixer | ||||
| Abstract | The superconducting energy gap is a fundamental characteristic of a superconducting film, which, together with the applied pump power and the biasing setup, defines the instantaneous resistive state of the Hot Electron Bolometer (HEB) mixer at any given bias point on the I-V curve. In this paper we report on a series of experiments, in which we subjected the HEB to radiation over a wide frequency range along with parallel microwave injection. We have observed three distinct regimes of operation of the HEB, depending on whether the radiation is above the gap frequency, far below it or close to it. These regimes are driven by the different patterns of photon absorption. The experiments have allowed us to derive the approximate gap frequency of the device under test as about 585 GHz. Microwave injection was used to probe the HEB impedance. Spontaneous switching between the superconducting (low resistive) state and a quasi-normal (high resistive) state was observed. The switching pattern depends on the particular regime of HEB operation and can assume a random pattern at pump frequencies below the gap to a regular relaxation oscillation running at a few MHz when pumped above the gap. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1558-2515 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1331 | |||
| Permanent link to this record | |||||
| Author | Korneeva, Y.; Sidorova, M.; Semenov, A.; Krasnosvobodtsev, S.; Mitsen, K.; Korneev, A.; Chulkova, G.; Goltsman, G. | ||||
| Title | Comparison of hot-spot formation in NbC and NbN single-photon detectors | Type | Journal Article | ||
| Year | 2016 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume |
26 | Issue | 3 | Pages | 1-4 |
| Keywords | NbC, NbN SSPD, SNSPD | ||||
| Abstract | We report an experimental investigation of the hot-spot evolution in superconducting single-photon detectors made of disordered superconducting materials with different diffusivity and energy downconversion time values, i.e., 33-nm-thick NbN and 23-nm-thick NbC films. We have demonstrated that, in NbC film, only 405-nm photons produce sufficiently large hot spot to trigger a single-photon response. The dependence of detection efficiency on bias current for 405-nm photons in NbC is similar to that for 3400-nm photons in NbN. In NbC, large diffusivity and downconversion time result in 1-D critical current suppression profile compared with the usual 2-D profile in NbN. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1348 | |||
| Permanent link to this record | |||||