Srubabati Goswami


Research Summary:

The physics implications of the second phase data from the SNO experiment have been examined. The effect of these data on the allowed ranges of the solar neutrino oscillation parameters, &Deltam212 and sin2&theta12, are studied in the cases of two- and three- neutrino mixing. In the latter case we obtain an upper limit on the angle &theta13. Constraints on the solar &nue transitions into a mixture of active and sterile neutrinos are also presented. Finally, we give predictions for the day-night asymmetry in the SNO experiment, for the event rate in the BOREXINO and LowNu experiments, and discuss briefly the constraints on the solar neutrino oscillation parameters which can be obtained with prospective KamLAND

A new reactor power plant Shika-2, with a power of approximately 4 GW and at a distance of about 88 km from the KamLAND detector is scheduled to start operating in March 2006. We have studied the impact of the

&nue flux from this reactor on the sensitivity of the KamLAND experiment to the solar neutrino oscillation parameters. We present results on prospective determination of Δm2 ${\odot}=1$ and sin2&theta${\odot}=1$ using the combined data from KamLAND and the solar neutrino experiments, including the effect of the Shika-2 contribution to the KamLAND signal and the latest data from the salt enriched phase of the SNO experiment. We found that contrary to the expectations, the addition of the Shika-2 reactor flux does not improve the sin2&theta${\odot}=1$ sensitivity of KamLAND, while the ambiguity in &Deltam2${\odot}=1$ measurement may even increase, as a result of the averaging effect between Kashiwazaki and the Shika-2 reactor contributions to the KamLAND signal.

We have also studied the physics potential of the KamLAND detector in probing neutrino oscillation parameters through observation of supernova neutrinos. In particular, we discuss the possibilities of probing the mixing angle &theta13 and determining the sign of Δm232 from the total charged current(CC) event rates on the proton and 12C target, as well as from the CC spectra. We discuss the chances of probing the earth matter effect induced modulations from the observation of CC spectra in the different CC reactions in KamLAND and find the volume required to get a statistically significant signature of the earth matter effect in different energy bins. We also calculate the event rates expected in the neutral current (NC) reactions on Carbon and free proton and investigate if the charged current to neutral current ratios, which are free of the absolute luminosity uncertainty in the supernova neutrino fluxes, can be useful in probing the oscillation parameters.


Publications:

  • Constraints on neutrino oscillation parameters from the SNO salt phase data.
    A. Bandyopadhyay, S. Choubey, S. Goswami, S. T. Petcov and D. P. Roy, Phys. Lett. B 583, 134.

  • On the measurement of solar neutrino oscillation parameters with KamLAND
    A. Bandyopadhyay, S. Choubey, S. Goswami and S. T. Petcov,
    arXiv:hep-ph/0309236, Phys. Lett. B 581, 62, (2003).

  • Exploring the sensitivity of current and future experiments to $\theta(\odot)$
    A. Bandyopadhyay, S. Choubey,S. Goswami, arXiv:hep-ph/0302243, to appear in Phys. Rev. D. Phys. Rev. D 67 113011, (2003).


Preprints:

  • Prospects of probing theta(13) and neutrino mass hierarchy by supernova neutrinos in KamLAND, A. Bandyopadhyay, S. Choubey, S. Goswami and K. Kar, arXiv:hep-ph/0312315

  • Solar neutrino oscillation parameters after KamLAND S. Goswami, A. Bandyopadhyay and S. Choubey, arXiv:hep-ph/0312028.

  • Solar Neutrinos and 1-3 mixing S. Goswami and A. Y. Smirnov, (in preparation).


Conference/Workshops Attended:

  • NANP' 03, Institute of Nuclear Research, Dubna, Russia, June 2003.

  • Discussion Meeting on Neutrinos, PRL , Ahmedabad

  • Workshop on High energy Physics, IIT, Mumbai


Visits to other Institutes:

  • Saha Institute of Nuclear Physics, Calcutta 1st - 3rd April, 1st -7th July, 2003.

  • SISSA, Trieste, 3rd - 20th June, 2003.

  • PRL, Ahmedabad, August 2003

  • ICTP, Trieste, 9th September - 3rd November, 2003.

  • Tata Institute of Fundamental Research, Mumbai 5th - 7th November, 2003

  • IIT, MUmbai 3rd - 14th January, 2004


Invited Lectures/Seminars:

  • Solar neutrino oscillation parameters after KamLAND ,NANP, DUbna, Russia, June 2003

  • Solar neutrino oscillation parameters after KamLAND , PRL, Ahmedabad, August 2003

  • Precision Measurement of solar neutrino oscillation parameters , ICTP, Trieste, October 2003

  • Precision Measurement of solar neutrino oscillation parameters TIFR, Mumbai, November 2003

  • Global Analysis of Neutrino Oscillation , PRL, Ahmedabad , March, 2004


Other Activities:

  • I have acted as the joint Co-ordinator, Astroparticle Physics group in WHEPP8, IIT, Mumbai January 2004.

  • I have taught the course on Mathematical Methods-II to first year graduate students.

  • Served in the computer committee and the medical committee as a member.

 



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