Observation of a KK enhancement at 1.85 GeV in the reaction K−p → KKΛ at 8.25 GeV/c

In a high statistics $\text{(}\text{～150 eV}\text{μb}\text{)}$ bubble chamber experiment on K^?p interactions at 8.25 $\text{GeV}\text{c}$, the study of the reaction K^?p → KKΛ provides evidence for an enhancement in the KK system with a mass of (1850 ± 10) MeV and a width of (80_?30⁺⁴⁰) MeV. Its possible identification with the missing isosinglet of the 3^? nonet is discussed. A K¹$\text{K}$ decay mode is also observed.     

Elastic scattering of α particles on light nuclei at Pα=7 GeV/c

Elastic scattering differential cross sections of α particles have been measured at P_α=7.0 GeV/c ($\text{T}\text{N}\text{=1.05}\text{GeV}$) on ¹H, ²H, ³He and ⁴He target up to a momentum transfer of ～4 (GeV/c)². A preliminary interpretation of the data is given in the framework of the Glauber theory.     

A Mössbauer study of amorphous Fe40Ni40B20

Amorphous Fe₄₀Ni₄₀B₂₀ (VITROVAC 0040) alloy has been investigated using ⁵⁷Fe Mössbauer Spectroscopy. The Curie temperature T_c is found to be well defined and is 695 ± 1 K. The quadrupole splitting just above T_c is 0.64 mm sec^?1. The crystallization temperature is 698 ± 2 K, close to but definitely above T_c. The average hyperfine field H_eff(T) of the glassy state shows a temperature dependence of $\text{H}{}_{\mathrm{<mtext>eff</mtext>}}\text{(0)[1 ? B}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{(T/T}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{? C}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{(T/T}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{? …]}$ indicative of the existence of spin wave excitations. The values of $\text{B}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{C}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ are found to be 0.40 and 0.06, respectively, for T/T_c ? 0.72. At temperatures close to T_c, H_eff(T) varies as (1 ? T/T_c)^β where β is one of the critical exponents and its value is found to be 0.29 ± 0.02.     

Critical behaviour of a uniaxial ferromagnet,ErCl3·6H2O with predominant dipolar interactions

The parallel magnetic susceptibility χ of a uniaxial ferromagnet ErCl₃·6H₂O has been measured between 0.3 and 4.2K and specially near T_c = 0.353 K. The predominant contribution to the Curie-Weiss temperature is due to the dipolar interactions. χ is proportional to ?^?γ with $\text{? =}\text{T}\text{T}{}_{\mathrm{c}}\text{?1}$ in the range 10^?3 < ? < 5 × 10^?2. The γ value, γ = 1.01 ±0.03 is consistent with the theoretical prediction for a uniaxial dipolar ferromagnet.     

Pseudoscalar mesons in the c-c and b-b systems

It is shown that the pseudoscalar η_c and “η_c” (η_b and “η_b”) with M ≈ 2.80 and 3.51 GeV (9.17 and 9.88 GeV) can be predicted by using the radial mixing model, where the “η_c” and “η_b” are the excited 0^- states in the $\text{c-}\text{c}$ and $\text{b-}\text{b}$ systems, respectively, and the former would correspond to the observed 0^- meson with M ≈ 3.45 GeV in charmonium.     

High pT π0 production from αα and αp collisions at the CERN ISR

The invariant cross sections for π⁰ meson production in alpha—alpha and alpha—proton collisions at the ISR were meas- ured up to transverse momenta of $\text{7}\text{GeV}\text{c}$ and $\text{8}\text{GeV}\text{c}$, respectively. These measurements are compared with π⁰ production in pp collisions at the same values of $\text{s}\text{/}$nucleon, and the variation of the nuclear A-dependence with p_T is determined.     

Satellite electron-diffraction in NbSe3 below T = 59 K

At temperatures below 59 K, coexistence of two types of satellite was observed in reciprocal lattice plane of b¹?c¹ as expressed by $\text{q}{}_1\text{= 0.24}\text{b}{}^1$ and $\text{q}{}_2\text{= 0.26}\text{b}{}^1\text{+0.50}\text{c}{}^1$. On the basis of nesting conditions by these q₁ and q₂, a feature of the Fermi surface for NbSe₃ is discussed.     

Evidence for a narrow peak in Ksoπ±π+π- at 2.6 gev in 12 gev/cpp interactions

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V⁰ topology of $\text{p}$p interactions at 12 GeV/c. The mass, widht and the product of cross section σ_I times the branching ratio BR into the final state (K_s^oτ±τ⁺τ^? are found to be: $\text{M}{}_{\mathrm{I}}\text{=2.60 ±}\text{0.01}\text{GeV}\text{/}\text{c}{}^2$, $\text{Γ}{}_{\mathrm{I}}\text{?}\text{0.018}\text{GeV}\text{/}\text{c}{}^2$, σ_I·BR≈20 μbarn     

KLo−KSo regeneration on deuterium

The K_L^o?K_S^o regeneration on deuterium has been measured at the 70 GeV Serpukhov accelerator in a momentum region of $\text{18–}\text{50}\text{GeV}\text{c}$. The measurements were performed by means of a 3 m long liquid deuterium target and an on-line spectrometer. The preliminary results on the energy dependence of the modulus and phase of the transmission regeneration amplitude are reported.     

Spin and lifetime of the ω− hyperon

A total of 101 ω^? decays have been found in K^?p interactions at 10 and $\text{16 GeV}\text{c}$. The decay angular distribution has been fitted under the assumptions that the ω^? has spin either $\text{1}\text{2}\text{or}\text{3}\text{2}$. It has been found that the probability of isotropy (spin$\text{1}\text{2}\text{)}$ is less than one in a thousand, whereas the probability for spin $\text{3}\text{2}$ is about 70%. Thus, we exclude the spin $\text{1}\text{2}$ assignment. The lifetime of the ω^? is found to be (1.41_?0.24^+0.15) × 10^?10s, in agreement with our earlier result based on about $\text{1}\text{5}$ of the present sample.     

Critical slowing down of fluctuations in squaric acid (H2C4O4) at the phase transition observed by 13C spin-lattice relaxation

Spin lattice relaxation T₁ of naturally abundant ¹³C nuclei in squaric acid was measured close to the antiferroelectric-paraelectric phase transition temperature T_c = 373 K. A rapid increase in $\text{1}\text{T}{}_1$ is observed close to T_c coming from above, which follows the power law $\text{1}\text{T}{}_1\text{～ ε}{}^{\mathrm{?1.4}}$ where $\text{ε =}\text{(T ? T}{}_{\mathrm{c}}\text{)}\text{T}{}_{\mathrm{c}}$. This behaviour is explained on the basis of the two-dimensional character of the fluctuations.     

Polymorphism in skinnerite,Cu3SbS3

Phase transitions in Cu₃SbS₃ are investigated under temperature variation using X-ray diffraction and nuclear quadrupole resonance. Below 263 K, Cu₃SbS₃ has the same structure as Wittichenite, the low temperature form of Cu₃BiS₃, space group P 2₁2₁2₁. Between 263 and 395 K it is monoclinic, space group P $\text{2}{}_1\text{c}$, and above 395 K it is orthorhombic, space, group Pnma with the high temperature Cu₃BiS₃ structure. At 295 K, Cu₃SbSe₃ has the orthorhombic space group Pnma with unit cell parameters $\text{a}\text{= 7.97}$, $\text{b}\text{= 10.61}$ and $\text{c}\text{= 6.83}\text{A}\text{?}$.     

Inclusive K1±(892) production in pp and π+p interactions

A study is presented of the inclusive production cross sections of K^1±(892) vector mesons in pp interactions at 12 and 24 GeV/c and in π⁺p interactions at 16 GeV/c. The K^1± inclusive cross section is ～0.9 mb for both pp at 24 GeV/c and π⁺p interactions at 16 GeV/c. For pp interactions, $\text{σ(}\text{K}{}^{\mathrm{1+}}\text{)}$ and $\text{σ(}\text{K}{}^{\mathrm{1?}}\text{)}$ are seen to rise with energy, showing a threshold behaviour. In both pp and π⁺p interactions, $\text{σ(}\text{K}{}^{\mathrm{1+}}\text{)}$ largely exceeds $\text{σ(}\text{K}{}^{\mathrm{1?}}\text{)}$ at these energies and this excess is interpreted as K¹⁺ production by beam and target fragmentations. The decays of K^1±0 yield ～30% of the K⁰ observed in the final states. The p_T² dependence of both K¹⁺ and K^1? cross sections is described by an exponential with slope of ～3.3 (GeV/c)^?2. The longitudinal momentum spectra for K¹⁺ in 16 GeV/cπ⁺p and 24 GeV/c pp interactions are similar in shape in the target hemisphere. The K^1? spectra are similar over the whole kinematic region when viewed in the quark c.m.s. and point to a central production mechanism. Comparing K¹⁺ and ρ⁰ production, striking similarities are found.     

The crystal structures of the ion conductors (NH+4)Zr2(PO4)3and (H3O+)Zr2(PO4)3

The crystal structures of (NH⁺₄)Zr₂(PO₄)₃ and (H₃O⁺)Zr₂(PO₄)₃ have been determined from neutron time-of-flight powder diffraction data obtained at 15 K. Both compounds are rhombohedral, $\text{R}\text{3}\text{c}$, with cell parameters a=8.7088(1) and c=24.2197(4) Å for the ammonium compound and a=8.7528(2), c=23.6833(11) Å for the hydronium compound. In both cases the ions are completely localized in the type I cavities and hydrogen bonded to lattice oxygens. The measured unit cell parameters are relatively large for this class of compounds but the entrance ways into the cavities are still too small to allow for unrestricted movement of the ions. Thus the low conductivity of the hydronium ion is related to this and other structural features.     

Anomalous phonon intensities in the Raman spectrum of disordered CsMg1−xCoxCl3

The five Raman-active $\text{k}\text{= 0}$ phonons have been measured at low temperatures and for a range of x in the disordered lattice CsMg_1-xCo_xCl₃. While the E_2g^a, E_2g^b, E_2g^c and A_1g modes at 55.0, 132.0, 189.0 and 255.0 cm^?1 for x = 0 exhibit normal one-mode behaviour, the intensity of the E_1g phonon at 127.5 cm^?1 has a most unusual concentration dependence which requires a new theory.     

Inclusive production of Ξ+ and Ξ− in K+ p interactions at 32 GeV/c

The inclusive production of $\text{Ξ}{}^{\mathrm{+}}$ and Ξ^? hyperons is investigated in K⁺ p interactions at 32 GeV/c. The production cross sections, 36.4±9 μb for the $\text{Ξ}{}^{\mathrm{+}}$ and 6.5±3 μb for the Ξ^?, are rising strongly with energy similarly to $\text{Λ}$ and Λ production in K⁺ p interactions. The $\text{Ξ}{}^{\mathrm{+}}$ are produced preferentially in the forward direction in the c.m.s., while the Ξ^? are produced dominantly backwards. The average transverse momenta and 〈p_T〉_Ξ^?=0.58±0.09 GeV/c.     

Energies of the n2S12 and n2D32,52 states of Cs

Using the technique of Doppler-free two-photon spectroscopy the energies of the n²S_{$\text{1}\text{2}$} (12 ? n ? 35) and n²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} (11 ? n ? 48) states of CsI have been measured with a thermionic detector. The absorption spectrum of molecular iodine was used as a reference giving us a total estimated accuracy of about 2 × 10^-7. Taking also into account the energies of the 7–11 ²S_{$\text{1}\text{2}$} and 5 and 6 ²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} states measured by other authors and using an extended Ritz-formula we found the ionization limit to be E_i = 31406.468 ± 0.006 cm^-1.     

Resonance production in the reaction π±p→Ks0K±p at 30 and 50 GeV/c

The mass and momentum transfer spectra of the charged $\text{K}\text{K}$ system produced in the reaction π^±p→K_s⁰K^±p are analyzed. The data have been collected at the CERN SPS with the Geneva-Lausanne two-arm, non-magnetic spectrometer at 30 and 50 GeV/c incident momenta. The general features of the reactions at these energies and the results of partial-wave analyses of the two kaon system are presented.The channel is dominated by the diffractive production of even spin resonances. The spin 4 recurrence of the A₂(1320) is clearly observed at 2040 MeV (Γ=380 MeV. A new resonance is observed with a mass M=2450MeV and a width Γ=400 MeV; the quantum numbers of this state are found to be I^G(J^PC)=1^?(6++). The analysis also shows the decay of the decay of the meson ?′(1600) through the $\text{K}\text{K}$ channel at both energies.The production amplitudes are determined both as a function of the $\text{K}\text{K}$ effective mass and of the momentum transfer. Isoscalar natural parity exchange is dominant. The energy dependence between 10 and 50 GeV/c is shown to be well described by a Regge pole model based on the f-dominated pomeron hypothesis. We compare the production mechanisms of the 2⁺ resonances A₂(1320) and K¹(1430). Finally, we estimate the $\text{K}\text{K}$ branching ratios of the spin 4 A₂(2040) and spin 6 A₂(2450) resonances.     

Off-shell NN annihilation studied in π+p interactions at 8 and 16 GeV/c

Interactions in which the baryon is emitted forwards in the c.m.s. are studied in 8 and 16 GeV/cπ⁺p collisions. These interactions are interpreted as representing baryon exchange. The properties of such off-shell $\text{N}$N annihilation events are studied. It is found that the multiplicity distribution of the multi-pion system as a function of the effective mass for events with |u_pp| < 1 GeV² is the same as for real $\text{N}\text{N}$ annihilations.     

Role of p-d hybridization in the Tc-variation of Y(Rh1−xRux)4B4 superconductors

Auger and photoemission studies for Y(Rh_1?xRu_x)₄B₄ superconductors elucidate the mechanism for the abrupt drop in T_c near x=0.5. The B $\text{p}$-states admix more strongly with Ru than Rh $\text{d}$-states, thereby yielding low-T_c values for Ru-rich compounds due to broadening of the $\text{d}$-band feutures. These effects underlie a previous suggestion that the preservation of Rh₄ tetrahedral units is essential for high-T_c values in ternary boride compounds.