Brookhaven High Flux Beam Reactor Research Articles

Gen Shirane

Gen Shirane

An accurate redetermination of the 118Sn binding energy

The energy of well-known strong γ line from 198Au, the “gold standard”, has been modified in the light of new adjustments in the fundamental constants and the value of 411.80176(12) keV was determined, which is 0.29 eV lower than the latest 1999 value. An energy calibration procedure for determining the neutron binding energy, B n, from complicated (n, γ) spectra has been developed. A mathematically simple minimization function consisting only of terms having as parameters the coefficients of the energy calibration curve (polynomial) is used. A priori information about the relationships among the energies of different peaks on the spectrum is taken into account by a Monte-Carlo simulation. The procedure was used in obtaining B n for 118Sn. The γ-ray spectrum from thermal neutron radiative capture by 117Sn has been measured on the IBR-2 pulsed reactor. γ-rays were detected by a 72 cm 3 HPGe detector. For a better determination of B n it was important to determine B n for 64Cu. This value was obtained from two γ-spectra. One spectrum was measured on the IBR-2 by the same detector. The other spectrum was measured with a pair spectrometer at the Brookhaven High Flux Beam Reactor. From these two spectra, B n for 64Cu was determined to be equal to 7915.52(8) keV. This result essentially differs from the previous value of 7915.96(11) keV. The mean value of the two most precise results of the B n for 118Sn, was determined to be 9326.35(9) keV. The B n for 57Fe was determined to be 7646.08(9) keV.

The production and X-ray structure determination of perdeuterated Staphylococcal nuclease

Staphylococcal Nuclease (SNase) has been chosen as a model protein system to evaluate the improvement in neutron diffraction data quality using fully perdeuterated protein. Large quantities of the protein were expressed in Escherichia coli grown in medium containing deuterated amino acids and deuterated water (D 2O) and then purified. The mean perdeuteration level of the non-exchangable sites in the protein was found to be 96% by electrospray ionization mass spectrometry. The perdeuterated enzyme was crystallized and its X-ray structure determined. Crystals of perdeuterated SNase have been grown to 1.5 mm 3. Crystallization conditions, space group and cell parameters were found to be the same for both native and perdeuterated forms of the protein. Comparison of these two forms of SNase revealed no significant structural differences between them at the atomic resolution of 1.9 Å. Data collection using crystals of the perdeuterated protein is scheduled at the Brookhaven High Flux Beam Reactor.

Structural Refinement of the High Temperature Form of Bi2MoO6

The structure of the high temperature polymorph of Bi2MoO6 has been determined by Rietveld powder refinement of high-resolution neutron diffraction data from the H1A diffractometer at the Brookhaven HFBR (high flux beam reactor). The cation distribution forms a fluorite-related supercell with infinite channels of bismuth polyhedra surrounded by molybdenum tetrahedra, in agreement with previously proposed models. The structure is refined in the monoclinic space group P 21/c to Rwp = 0.134 and R1 = 0.084 (Rexp = 0.024) from 2559 reflections: a = 17.2627(1) A, b = 22.4296(2) A, c = 5.58489(5) A, β = 90.4974(6)°, Z = 16. Bond valence sums and site potentials have been calculated which reveal evidence for significant charge transfer in this structure. The relationship of this phase to other catalytically-active bismuth molybdates is discussed.

A hybrid beam design for slow positron transport

The authors report on the design of a hybrid transport system for slow positrons based upon the high-intensity magnetically transported positron beam, which existed at the Brookhaven (BNL) high-flux beam reactor (HFBR) in 1986. The resulting modified transport, incorporating an initial electrostatic stage followed by a magnetic stage and completed by brightness enhancement moderation leading to a final electrostatic section, represented the minimum alteration of the existing beam to enable it to be used for crossed-beams differential scattering studies involving a variety of atomic and molecular systems, including atomic hydrogen. A recent proposal for constructing a very high-intensity positron beam at the Paul Scherrer Institute (PSI), based upon magnetic confinement premoderation, has rekindled interest in the conclusions of the study.

A New High Resolution Neutron Powder Diffractometer at the Brookhaven High Flux Beam Reactor

A high resolution neutron powder diffractometer under construction at the Brookhaven HFBR is expected to be completed by mid-1991. The new machine will have a Ge (511) monochromator with a take-off angle of 120{degree} ({lambda} = 1.89{angstrom}) and 64 {sup 3}He counters in the detector bank. There will be interchangeable collimators before the monochromator allowing a choice of 5 or 11 ft horizontal divergence, and 10 cm-high, 5 ft collimators in front of the detectors. In the higher resolution mode, {Delta}d/d is expected to be about 6 {times} 10{sup {minus}4} at the resolution minimum. The diffractometer is generally similar to D2B at the Institut Laue- Langevin except for the monochromator. This will consist of a vertically focussing array of segments 3 {times} 1.27 cm in dimensions cut from stacks of 20 0.43 mm wafers that have been pressed and brazed together. Preliminary measurements indicate that a mosaic width of 0.1--0.15{degree} and a peak reflectivity of 25% can be achieved in this way. 22 refs., 2 figs., 1 tab.

A new facility for averaged resonance capture studies at the Omega West reactor

A facility has been developed at the Omega West reactor at Los Alamos to provide neutron beams of 2 and 24 keV average neutron energies. The neutron beam currents are comparable with those obtained at the Brookhaven high flux beam reactor. A three-crystal pair spectrometer has been developed to allow acquisition of high resolution primary neutron capture gamma ray spectra. This will be used for nuclear spectroscopy and structure studies.

Magnetic structure of the heavy-fermion compound U2Zn17.

PHYSICAL REVIE%' VOLUME 33, NUMBER 5 Magnetic structure of the heavy-fermion compound MARCH 1986 U2Znt7 D. E. Cox, G. Shirane, and S. M. Shapiro Physics Department, A Tcf T Brookhaven National Laboratory, Bell Laboratories, Upton, New York G. Aeppli 600 Mountain Avenue, Murray Hill, New Jersey 07974 Z. Fisk and J. L. Smith Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 l. Kjems Risd National Laboratory, Roskilde, Denmark H. R. Ott Laboratorium I'ur I estkorperphysik, Eidgenossische Technische Hochschule-Honggerberg, 8093 Zurich, Switzerland (Received 26 September 1985) The phase transition of U2zni7 at 9. 7 K has been investigated by neutron powder diffraction. The transi- tion corresponds to the onset of antiferromagnetic order where the U moments are oriented antiparallel to their nearest neighbors within the basal planes and the near neighbor along the c axis of this rhombohedral compound. At 5 K, the ordered moments lie within the basal planes and are of magnitude (0. 8+0. 1) p, &, which is substantially below the paramagnetic moment of 2.25', &/U atom given by high-temperature sus- ceptibility data. The list of heavy-fermion systems, which display ex- traordinarily large ( & 400m, ) effective conduction electron masses as deduced from the low-temperature specific heat, and metals remaining now includes both superconductors Recent magnetic paramagnetic to the lowest temperatures. susceptibility and specific-heat measurements suggest that there are also heavy-fermion systems which undergo transi- tions to magnetically ordered ground states. ' In this paper, we present the first neutron-scattering determination of magnetic order in a heavy-fermion system, U2Zni7. The essential results are as follows. First, the ordering, which 10 K, is exceedingly simple, with the mag- sets in at T~ netic unit cell identical to the nuclear unit cell, and the mo- ments associated with the two U atoms in the primitive unit cell oriented in opposite directions. Second, the ordered moment is (0. 8+0. 1)p, s/U atom which is well below the moment of 2. 25@, s /U atom deduced from the high- temperature (bulk) susceptibility. U2Zni7 was made by heating the appropriate amounts of U and Zn to 1050'C in an evacuated BeO crucible. Ap- proximately 20 g of material were crushed into a coarse pounder and loaded into a cylindrical aluminum sample hold- er in an atmosphere of helium. Data were collected at the Brookhaven High Flux Beam Reactor with 2.353-A neu- trons from a pyrolytic-graphite monochromator in the (002) filter suppressed higher-order setting. A pyrolytic-graphite wavelengths. For the structure determination at 15 K ( T~), a pyrolytic-graphite analyzer in the (004) setting was used in order to optimize the resolution at higher scattering angles. The collirnations were 20'-open-40'-20' for in-pile, monochromator-sample, sample-analyzer, and analyzer-detector, respectively. The resulting diffraction pattern showed a number of weak impurity peaks in addi- tion to those characteristic of U2Zni7. The major impurity was identified as Zn, estimated to be about 5'/0 by weight. The remaining peaks were an order of magnitude weaker «1% of the strong U2Zn~7 peaks) and (with intensities could not be identified. The d spacings are listed in the cap- tion to Fig. 1, and do not correspond to those of UZni2 or e-U. At room temperature, U2Zn&7 (Ref. 3) has the Th2Zn~7- type structure, which is one of a series of ordered structures [e. g. , Pu3Zn22, UZnt2 (Ref. 5)] which can be derived from that of CaCu5. In U2Zni7, Zn occupies the Cu sites and U is ordered on two-thirds of the Ca sites, the remaining one- third being replaced by pairs of Zn atoms about 2. 6 A apart. The ordered structure has rhombohedral symmetry, space group R3m, with hexagonal lattice constants v 3a and 3c with respect to those of the parent CaCu5-type cell. Be- cause the structural parameters for U2Zni7 near its 10-K transition were unknown, we carried out a Rietveld analysis of the data sho~n in Fig. 1. Regions around the impurity peaks and Al reflections from the sample holder were ex- cluded from the refinement, and background contributions were estimated by interpolation between values obtained by averaging over regions where no Bragg peaks were present. Table I displays the lattice parameters and atomic coordi- nates given by the profile refinement. In the upper frame of Fig. 1, the solid line represents the calculated profile which best fits the data, while in the lo~er frame, the difference between the calculated and observed profiles is shown. The results are in exce11ent agreement with a room-temperature x-ray scattering determination of the structure. Belo~ 10 K some very weak additional scattering at some of the low-angle nuclear peak positions was observed. To gain more intensity tics to be obtained and thus allow adequate counting statis- in a reasonable period of time, the

A neutron diffraction study of [N(PPh3)2]+[B2H7]–·CH2Cl2at 80 K

The structure of the [B2H7]– anion, reported by us earlier in an X-ray structure determination, has been analysed more accurately by neutron diffraction. Data were collected at 80 K on a sample of [N(PPh3)2]+[B2H7]–·CH2Cl2 using the Brookhaven High Flux Beam Reactor. The essential results of the X-ray analysis are confirmed, with more accurate molecular parameters. The [B2H7]– anion has a non-crystallographic Cs symmetry, with a bent geometry [B–H–B 127(2)°] and staggered terminal B–H bonds. Average terminal and bridging B–H bond lengths are 1.18(2) and 1.27(6)Å respectively, and the B ⋯ B distance is 2.27(1)Å. There is a slight asymmetry of the B–H–B bridge [B(1)–H 1.32(2), B(2)–H 1.21(2)Å], which is on the borderline of being significant. [N(PPh3)2]+[B2H7]–·CH2Cl2 crystallizes in the triclinic space group P, with a= 9.633(1), b= 10.513(1), c= 16.938(1)Å, α= 90.599(7), β= 93.142(8), γ= 93.744(8)°, and Z= 2 at 80 K. The final R factor is 0.096 for the 1 479 reflections with Fo2 > 3σ(Fo2).

X-ray and neutron diffraction studies of the polyhydrido complex FeH6Mg4Br3.5Cl0.5(C4H8O)8: discussion of binary transition-metal hydride anions of the type [MHx]n-

The molecular structure of the polyhydrido complex FeH6Mg4X4(THF)8 (X4 = Br/sub 3.5/Cl/sub 0.5/) has been determined by single-crystal X-ray and neutron diffraction methods. The X-ray structure determination was carried out at room temperature, revealing an octahedral (FeH6)U core with (MgBr(THF)2) units situated over four of the eight faces of the octahedron. The (FeH6)U core exhibits crystallographic twofold symmetry, with an average Fe-H distance (as determined in the X-ray study) of 1.69 (9) A. Neutron diffraction analysis of the title compound (carried out at 80 K at the Brookhaven High-Flux Beam Reactor on a crystal of volume 12 mmT) fully confirmed this basic molecular geometry, yielding much more precise H positions. The Fe-H (1.609 (2) A) and Mg-H (2.045 (18) A) distances obtained from the neutron study support the idea that the Fe-H bond is largely covalent in nature while the Mg-H interaction is largely ionic. A detailed discussion of available structural information for binary transition-metal hydride anions, (MH/sub x/)/sub n-/, is given in the text. Crystallographic details for the X-ray analysis of the title compound C32H70Br/sub 3.5/Cl/sub 0.5/FeMg4O8 is included. Details for the neutron analysis at 80 Z are also reported. 52 references, 2 figures, 4 tables.

An experimental study of the critical fluctuations in a two-dimensional Ising model

Neutron scattering measurements have been made of the critical fluctuations in K2CoF4 at the Brookhaven High Flux Beam reactor. The critical fluctuations were studied for both temperatures above and below Tc. Above Tc the scattering is well described by the Ornstein-Zernike form and the exponents and amplitude of kappa (the inverse correlation length) are in excellent accordance with theory. Below Tc the Ornstein-Zernike form gives a reasonable description of the results, but the resulting kappa are very different from those expected theoretically. The approximate form developed by Tarko and Fisher (1975) gives a better description of the results and the resulting parameters are in accordance with theoretical expectations. The authors conclude that the critical fluctuations in the d=2 Ising model are not described by the Ornstein-Zernike form. The amplitude ratios have been measured for the correlation length, the susceptibility, and the ratio connecting the Bragg scattering to the susceptibility by using two-scale-factor universality. The results in each case agree with theory to within the experimental error which varies between 10 and 15%.

A Memory Intensive Functional Architecture for Distributed Computer Control Systems

A memory-intensive functional architecture for distributed data-acquisition, monitoring, and control systems with large numbers of nodes has been conceptually developed and applied in several large-scale and some smaller systems. This discussion concentrates on (a) the basic architecture; (b) recent expansions of the architecture which now become feasible in view of the rapidly developing component technologies in microprocessors and functional large-scale integration circuits; (c) implementation of some key hardware and software structures and one system implementation which is a system for performing control and data acquisition of a neutron spectrometer at the Brookhaven High Flux Beam Reactor. The spectrometer is equipped with a large-area position-sensitive neutron detector.

Structural temperature dependence in α-lithium iodate: Neutron and x-ray study between 20 and 500 K

The crystal structure of hexagonal α-LiIO3 has been determined by neutron and x-ray diffraction at ten temperatures from 20 to 500 K. Four sets (1248 to 1622 reflections per set) of neutron data at λ=1.0467 Å were measured at the Brookhaven High Flux Beam Reactor at 20, 100, 200, and 295 K. The integrated intensities of a further 13 data sets (1706 to 2963 reflections per set) were measured using MoKα radiation on a CAD-4 x-ray diffractometer. The structure at each temperature was refined by least squares in space group P63. The final agreement factors fell between 0.023 and 0.050. The unit cell dimensions at 295 K are a=5.481 27(6), c=5.171 65(4) Å, with nonlinear thermal expansions. The principal change in structure with temperature is in the atomic positions of Li and O relative to I: The positions are given by O(z)T=−0.8435(3) Å+62(4)×10−9 T2 Å K−2 and Li(z)T=0.3808(10) Å+167 (18)×10−9 T2 Å K−2. The iodate ion has a constant I–O bond length of 1.8081(4) Å, but the O–I–O angle increases from 99.97(2)° at 20 K by 0.5° over the temperature range studied. The LiO6 octahedron has Li–O distances of 2.070 and 2.140(1) Å at 20 K, increasing to 2.106 and 2.151(9) Å at 460 K. The mean-square amplitude of thermal vibration varies nonlinearly with temperature for all atoms, with zero-point rms displacement of 0.040 Å for I, 0.067 Å for O, and 0.094 Å for Li. The Debye temperature is estimated as 350 K on the basis of the 295 K amplitudes of vibration.

A Memory Intensive Functional Architecture for Distributed Computer Control Systems

A memory-intensive functional architecture suitable for distributed data acquisition, monitoring and control systems with large numbers of microprocessor based nodes has been conceptually developed and applied in several large scale and some smaller systems. This discussion concentrates on (a) the basic architecture; (b) expansions as they become feasible in view of continuing rapid developments in the microprocessor technology and in functional large-scale integration circuits; (c) the implementation of some key hardware and software structures; and (d) two system implementations, which are (1) a system for monitoring and managing of animal inhalation chambers and restricted access rooms as well as for experimental data acquisition and data analysis at an Inhalation Toxicology Research Facility and (2) a data acquisition and control system for a spectrometer with a 20 by 20 cm position-sensitive detector used in neutron scattering experiments at the Brookhaven High Flux Beam Reactor.

Low-temperature (20 K) neutron diffraction study of [K(crypt-222)]+[Cr2(CO)10(.mu.-H)]-. Influence of the lattice environment and the K+ ion on the anion's metal carbonyl framework and the ordered chromium-hydrogen-chromium bond

A combination room-temperature x-ray and low-temperature (20 +- 1 K) neutron diffraction study of (K-(C/sub 18/H/sub 36/N/sub 2/O/sub 6/))/sup +/(Cr/sub 2/(CO)/sub 10/(..mu..-H))/sup -/ has been performed to determine the anion's configuration in the absence of crystallographic site symmetry constraints. Although the K/sup +/ ion is surrounded by the cryptate molecule, the ion influences the anion's solid-state structure. The relatively close separation of 2.966 (3) A between the K/sup +/ ion and 01 of the anion is nearly equal to the sum of the corresponding ionic radii of ca. 2.9 A and thereby suggests the presence of an appreciable cation-anion interaction. Although this attractive interaction does not noticeably perturb the local C/sub 4 sigma/ symmetry of the respective Cr(CO/sub 5/ fragment, it causes the anion's eclipsed metal carbonyl structure to undergo a twisting distortion toward a previously unobserved bent structure. The two independent Cr(CO)/sub 5/ groups of the anion are rotated ca. 19/sup 0/ with respect to each other about the Cr-Cr line. This configurational change in the metal carbonyl framework is accompanied by a reduction of the Cr-Cr separation to 3.300 (4) A and the Cr-H-Cr bond angle to 145.2 (3)/sup 0/, which collectively imply an increase in the metal-metalmore » bonding component of the closed three-center, two-electron Cr-H-Cr bond. The ordered bridging hydrogen atom resides in a symmetrical electronic environment as suggested by the two independent, but equivalent, Cr-H separations of 1.735 (5) and 1.723 (5) A. These Cr-H distances are comparable in magnitude to the corresponding distances in the (Et/sub 4/N)/sup +/ and ((Ph/sub 3/P)/sub 2/N)/sup +/ salts. The neutron diffraction data were measured with an automated four-circle diffractometer at the Brookhaven high-flux beam reactor.« less

The effect of neutron irradiation upon the superconducting critical temperature of some transition-metal carbides, nitrides, and carbonitrides

Samples of TiN, NbC, and Nb(CN) have been irradiated to various neutron doses in the Brookhaven High Flux Beam Reactor. Their superconducting critical temperatures are reduced at a rate which is much less than that for similarly irradiated high-Tc A15 superconductors. A dose of 1.5×1020 n/cm2 (E≳1 MeV) causes a reduction in Tc of 6–27%. This reduction may be explained in terms of the production of metal-lattice vacancies.

Spin fluctuations in random magnetic-nonmagnetic two-dimensional antiferromagnets. III. An Ising system

This paper reports a study using neutron scattering techniques of the spin fluctuations in the two-dimensional diluted Ising system, ${\mathrm{Rb}}_{2}{\mathrm{Co}}_{c}{\mathrm{Mg}}_{1\ensuremath{-}c}{\mathrm{F}}_{4}$. The explicit concentrations studied, $c=0.55,0.575,0.585,\mathrm{and} 0.595$ are all close to the percolation concentration for nearest-neighbor interactions ${c}_{p}=0.594$, so that these experiments span the percolation threshold. The experiments were performed at the Brookhaven high-flux beam reactor. A detailed study was made of the dynamics for $c=0.575$. The results showed four dispersionless bands corresponding to spin deviations on Co ions surrounded by one, two, three, or four Co ions. Calculations of the spectra using the equation-of-motion method for computer simulations gave a good account of the results. The few minor discrepancies probably arise from the effects of those crystal-field levels of the Co ion which have energies above the ground-state doublet. The $c=0.595$ crystal has a transition at 30 K to a state of two-dimensional order with negligible order in the third direction. The inverse correlation length in this system is zero to within the errors at 30 K. In the more dilute systems the inverse correlation length is found to be well described as an additive sum of a geometrical and a thermal part as observed previously in ${\mathrm{Rb}}_{2}{\mathrm{Mn}}_{c}{\mathrm{Mg}}_{1\ensuremath{-}c}{\mathrm{F}}_{4}$. The thermal part is given by ${[{\ensuremath{\kappa}}_{1}(T)]}^{1.32\ifmmode\pm\else\textpm\fi{}0.05}$ where ${\ensuremath{\kappa}}_{1}(T)$ is the inverse correlation length of a one-dimensional chain of Co ions. This exponent is consistent with the percolation exponent ${\ensuremath{\nu}}_{p}=1.35$ and the theoretically calculated crossover exponent, $\ensuremath{\varphi}=1$. The intensity of the scattering is more difficult to analyze in the absence of a knowledge of the form of the scaling function, but the behavior is consistent with the multicritical picture with $\ensuremath{\varphi}=1$.

The Brookhaven Reactor Experiment Control Facility - A Distributed Function Computer Network

A computer network for real-time data acquisition, monitoring and control of a series of experiments at the Brookhaven High Flux Beam Reactor has been developed and has been set into routine operation. This Reactor Experiment Control Facility presently services nine neutron spectrometers and one x-ray diffractometer. Several additional experiment connections are in progress. The architecture of the facility is based on a distributed function network concept as introduced and defined elsewhere. This paper is a statement of implementation and results.

Hydrogen bond studies. 85. A very short, asymmetrical, intramolecular hydrogen bond: A neutron diffraction study of pyridine-2,3-dicarboxylic acid (C7H5NO4)

A neutron diffraction study of pyridine-2,3-dicarboxylic acid (quinolinic acid) has been carried out. The intensities for 3780 reflexions were measured at the Brookhaven High Flux Beam Reactor. The structure was refined to an R(F2) of 0.054 using starting parameters from a previous x-ray study. The short intramolecular hydrogen bond [O ··· O: 2.398(3) Å] has no symmetry restriction operating on the hydrogen atom position and is asymmetric. The two O ··· H distances are 1.163(5) and 1.238(5) Å, respectively, and the O–H–O angle is 174.4(4)°. The asymmetry of the bond can be explained by the intramolecular environment. The strain in the molecule caused by the short hydrogen bond results in long carbon-carbon bonds to the carboxyl groups [1.516(2) and 1.541(2) Å]. The C–O bond lengths [1.219(3), 1.263(2), 1.222(3), and 1.270(2) Å] vary depending on the hydrogen-bond involvement of the oxygen atoms. The mean C–H distance is 1.087 Å and the N–H distance is 1.036(4) Å. The nitrogen atom is involved in an intermolecular N–H ··· O hydrogen bond [N ··· O: 2.725(2), H ··· O: 1.845(4) Å and angle N–H ··· O: 140.5(2)°]. There are a number of short intermolecular O ··· H–C contacts. The refined neutron scattering length for the nitrogen atom is b̄N=0.925(4)×10−12 cm.

Radiative decay of neutron resonances inGe73(n,γ)Ge74

$\ensuremath{\gamma}$ rays following neutron capture in natural germanium have been studied up to ${E}_{n}\ensuremath{\approx}500$ eV with the fast chopper at the Brookhaven high flux beam reactor. Up to this energy only resonances in $^{73}\mathrm{Ge}$ contribute. From the high-energy $\ensuremath{\gamma}$ rays observed, levels in $^{74}\mathrm{Ge}$ are identified to an excitation energy of about 3 MeV. From the low-energy $\ensuremath{\gamma}$ rays depopulating the $^{74}\mathrm{Ge}$ levels, spin assignments for several $^{73}\mathrm{Ge}$ resonances are made; namely 102 eV, ${J}^{\ensuremath{\pi}}={4}^{+}$; 204 eV, ${J}^{\ensuremath{\pi}}={5}^{+}$; and 224 eV, ${J}^{\ensuremath{\pi}}={4}^{+}$. The results of the resonance capture experiments are compared to previous "average-resonance" and thermal-capture work, and in general are found to be in good agreement. Average radiative strengths for $M1$ and $E2$ transitions are calculated and compared to model estimates.[NUCLEAR REACTIONS $^{73}\mathrm{Ge}(n,\ensuremath{\gamma})^{74}\mathrm{Ge}$, in resonances to 400 eV; energy levels in $^{74}\mathrm{Ge}$, ${J}^{\ensuremath{\pi}}$, resonance spins, ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\lambda}f}$; photon strength functions.]