• Volume 4, Issue 5

      May 1975,   pages  199-245

    • A study of erbium, thulium and other rare earth ethyl sulphates

      Vishwamittar S P Puri

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      The available sets of crystal field parameters for erbium and thulium ethyl sulphates are used to calculate the Stark levels,g-values, Schottky specific heat, magnetic anisotropy, hyperfine interaction parameters and low temperature specific heat of these compounds. A comparison of these calculations with experimental data shows that one of these sets can be taken to be optimum within the accuracy of various measurements. These parameters along with the already optimised ones for other ethyl sulphates are discussed in the frameworks of electrostatic, angular overlap and superposition models for the crystalline fields. The antibonding energy parameter and ionicity are found to be different for light and heavy compounds and almost constant in either half of the series.

    • Elastic constants of sodium chlorate from 77 K to 350 K

      K R Srinivasan E S R Gopal J Ramakrishnan S Krishnan

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      The elastic constantsC11,C12 andC44 of sodium chlorate single crystal have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values areC11=4.90,C12=1.39,C44=1.17 (× 1010N/m2) at 298 K and 6.15, 2.16, 1.32 (×1010N/m2) at 77 K. The data agree well with the values measured earlier up to 223 K. Brief mention is also made of the low temperature bonding problems in these soft crystals.

    • K-capture probability in the decay of139Ce(137.5d)

      B K Dasmahapatra

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      The K-capture probability (PK) in the decay of139Ce (137.5d) has been determined from the analysis of the K x-ray gamma ray sum-peak observed with a Ge (Li) x-ray detector. Furthermore,PK is estimated independently from the measurement of the K x-ray intensity in the decay, using the known conversion coefficients of the 165.8 keV transition. Using the weighted average ofPK measured as above, the mass difference between139Ce and139La is found to be 273−13+21 keV.

    • Effect of gluons on neutral-current interactions in deep inelastic neutrino scattering

      G Rajasekaran Probir Roy

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      The contribution of neutral spin-1 gluons to the deep inelastic neutral-current processesv(v)+Nv(v)+ hadrons is worked out in the parton model. Such a contribution violates Bjorken scaling strongly.

    • Characteristics of a high frequency ion source used in a low-energy accelerator

      Mohamed E Abdelaziz Mohamed A Eid Fatma Abdelsalam

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      This work presents the characteristics of a high frequency ion source operating on a low energy, 150 keV accelerator. The latter is to be used as a neutron generator and its design is based on a theoretical analysis which shows that if the axial potential in an electrostatic electrode system is made to increase with four thirds the power of axial distance, inward electric forces will compensate space charge forces tending to blow up the beam. This results in a simplified acceleration tube much shorter and of higher gradient than the conventional acceleration columns. The ion source itself is an ordinary type using axial extraction of the beam, and its main properties investigated are the beam current and beam quality (or emittance). Dependence of the two on different parameters is investigated in a series of tests.

    • Hölder’s inequality for matrices

      C L Mehta

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      We prove that for arbitraryn×n matricesA1,A2,…,Am and for positive real numbersp1,p2,…,pm withp1−1+p2−1+…+pm/−1=1, the inequality$$|Tr(A_1 A_2 ...A_m )^2 |< \mathop {II}\limits_{k = 1}^m [Tr(A_k^\dag A_k )^{p_k } ]P_k^{ - 1} $$ holds.

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