Search for anomalous interaction mean free paths of charge, 2≦Z≦18 projectile fragments in emulsions exposed to 1.8 A GeV40Ar ions

⁴⁰Ar-emulsion interactions are studied, to investigate the question of anomalons, in twoG- 5 emulsion stacks. In about 4600 primary interactions, projectile fragments of Z≧2 for all generations have been followed until they interact or leave the stack. After careful estimation of charges of these fragments, variation of their mean free paths is studied as a function of distance from the preceding interaction. Generation effect,N _h dependence and production angle effect are investigated. In addition multi-chain events are analysed separately. Our results do not show anomalons at the 6% level and are consistent with non-occurrence of anomalons. However, this experiment is not sensitive enough to rule out anomalons (with a mfp of the order of 2 to 3 cm) produced at about 1% (or less) level.     

Observation of inter-grain Josephson effects in Y-Ba-Cu-O samples

Josephson effects have been observed in bulk samples of Y-Ba-Cu-O. The magnitude of the zero-voltage current is found to change systematically with externally applied small magnetic fields of a few mG. It is also found to vary when samples are irradiated with microwaves. These observations suggest the presence of inter-grain Josephson junctions.     

An investigation of FeCoCrO4 by Mossbauer spectroscopy

The spinel FeCoCrO₄ has been studied between 4.2 and 538°K. Characteristic Mossbauer spectra of paramagnetic, magnetic and electronic relaxation types have been observed. The Mossbauer parameters for Fe³⁺ ions situated at tetrahedral (A) and octahedral (B) sites have been calculated. The cation distribution in magnetic and paramagnetic phases is found to be approximately Fe_0.5³⁺Co_0.5²⁺[Co_0.5²⁺Fe_0.5³⁺Cr³⁺]O₄. The Neel temperature been determined by the temperature scanning method to be 310±5°K.     

Temperature dependence of Van Vleck susceptibility in pyrite (FeS2)

We present here a discussion of the temperature (T) dependence of Van Vleck susceptibility (χ_νν) in pyrite. Using the reported experimental values of energy gap E_G and χ_νν at various temperatures, we evaluate the percentage change in χ_νν with respect to temperature due to changes in E_G and a term due to virtual magnetic dipole transitions between states on the same site. This study leads us to believe that, with increase in temperature, the contribution to percentage change in χ_νν due to such transitions is negative while the contribution from E_G is positive.     

Effect of methylene blue on the capacity of the dropping mercury electrode

Summary The effect of methylene blue under different conditions of p_H, concentration and frequency of the a. c. ripple used has been investigated on the capacity of the dropping mercury electrode. All the peaks caused by methylene blue at different p_H values have been interpreted as due to the reduction of the methylene blue, as indicated by the comprehensive study of the peaks. The halt at about 0.58 Volt at p_H 5.8 is due to desorption which develops into a satellite peak if potassium nitrate is used as indifferent electrolyte. It is found that the peak at 1.35 Volt at p_H 12.3, first increases with increase in concentration and then diminishes at still higher concentrations. The causes of this have been discussed. The effect of frequency reveals that the reduction reactions involved are rather slow.

---

Zusammenfassung Der Effekt von Methylenblau unter verschiedenen Verh?ltnissen von Wasserstoff-Ionen-Konzentration, Konzentration und Frequenz des überlagerten Wechselstroms auf die Kapazit?t der Quecksilbertropfelektrode war Gegenstand der Untersuchung. Alle dem Methylenblau zuzuschreibenden Maxima bei verschiedenen p_H- Werten lassen sich interpretieren durch eine Reduktion des Methylenblau, wie die eingehende Untersuchung der Maxima zeigt. Der Konstanzbereich bei etwa 0,58 Volt und p_H 5,8 ist einer Desorption zuzuschreiben, die ein Begleitmaximum entwickelt, wenn Kaliumnitrat als indifferenter Elektrolyt verwendet wird. Das Maximum bei 1,35 Volt und p_H 12,3 w?chst zun?chst bei Steigerung der Konzentration und nimmt dann bei noch h?heren Konzentrationen wieder ab. Die Gründe hierfür werden diskutiert. Der Frequenzeffekt zeigt an, da? die Reduktionsreaktionen ziemlich niedrig sind.

     

Gravimetric determination of thorium and zirconium

Summary Thorium and zirconium can be quantitatively precipitated by quinaldinic acid atph 2.7 and 3, respectively. As the precipitates are of nonstoichiometric composition they are to be ignited to oxides. By this reagent thorium can be quantitatively separated from arsenic (As³⁺), mercury (Hg²⁺), rare earths, manganese, magnesium and alkaline earths and zirconium from all the aforesaid ions excepting rare earths which contaminate to a slight extent.