arXiv subjects

Sanjib Kumar Agarwalla

Publications and source records attributed to Sanjib Kumar Agarwalla.

90 records · Page 5Linked to original sources

arXiv2011

New approach to anti-neutrino from muon decay at rest

Neutrino physics is going through a very exciting phase. In last one and half years, crucial informations have been provided by both short and long baseline neutrino oscillation experiments. At short-baseline, recent neutrino oscillation studies seem to point towards the existence of active-sterile mixing. On the other hand at long-basline, recent T2K and MINOS data are in favor of non-zero theta13 opening up the possibility of observing CP-violation in the lepton sector. A stopped pion source provides neutrino beams with energy of a few tens of MeV from pion and muon decay-at-rest. A rich physics program can be accomplished with such a neutrino source. We discuss the role of such a neutrino facility to test short-baseline anomalies and to study CP violation in active neutrinos.

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arXiv2011

Short-baseline Neutrino Oscillation Waves in Ultra-large Liquid Scintillator Detectors

Powerful new multi-kiloton liquid scintillator neutrino detectors, including NOvA and LENA, will come on-line within the next decade. When these are coupled with a modest-power decay-at-rest (DAR) neutrino source at short-baseline, these detectors can decisively address the recent ambiguous signals for neutrino oscillations at high Delta m^2. These detectors are > 50 m long, and so with a DAR beam, the characteristic oscillation wave will be apparent over the length of the detector, providing a powerful verification of the oscillation phenomena. LENA can simultaneously perform numubar to nuebar appearance and nue to nue disappearance searches with unprecedented sensitivity. NOvA is likely limited to nue disappearance given its present design, but also has excellent sensitivity in the high Delta m^2 region. For the appearance channel, LENA could provide a stringent test of the LSND and MiniBooNE signal regions at > 5 sigma with a reduced fiducial volume of 5 kt and a 10 kW neutrino source. In addition, the LENA and NOvA disappearance sensitivities in nue mode are complementary to the recent reactor anomaly indicating possible nuebar disappearance and would cover this possible oscillation signal at the 3 sigma level.

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arXiv2011

Optimization of the Neutrino Factory, revisited

We perform the baseline and energy optimization of the Neutrino Factory including the latest simulation results on the magnetized iron detector (MIND). We also consider the impact of tau decays, generated by nu_mu to nu_tau or nu_e to nu_tau appearance, on the mass hierarchy, CP violation, and theta_{13} discovery reaches, which we find to be negligible for the considered detector. For the baseline-energy optimization for small theta_{13}, we qualitatively recover the results with earlier simulations of the MIND detector. We find optimal baselines of about 2500 km to 5000 km for the CP violation measurement, where now values of E_mu as low as about 12 GeV may be possible. However, for large theta_{13}, we demonstrate that the lower threshold and the backgrounds reconstructed at lower energies allow in fact for muon energies as low as 5 GeV at considerably shorter baselines, such as FNAL-Homestake. This implies that with the latest MIND analysis, low- and high-energy versions of the Neutrino Factory are just two different versions of the same experiment optimized for different parts of the parameter space. Apart from a green-field study of the updated detector performance, we discuss specific implementations for the two-baseline Neutrino Factory, where the considered detector sites are taken to be currently discussed underground laboratories. We find that reasonable setups can be found for the Neutrino Factory source in Asia, Europe, and North America, and that a triangular-shaped storage ring is possible in all cases based on geometrical arguments only.

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arXiv2010

Constraining sterile neutrinos with a low energy beta-beam

We study the possibility to use a low energy beta-beam facility to search for sterile neutrinos by measuring the disappearance of electron anti-neutrinos. This channel is particularly sensitive since it allows to use inverse beta decay as detection reaction; thus it is free from hadronic uncertainties, provided the neutrino energy is below the pion production threshold. This corresponds to a choice of the Lorentz gamma=30 for the 6He parent ion. Moreover, a disappearance measurement allows the constraint of sterile neutrino properties independently of any CP violating effects. A moderate detector size of a few 100 tons and ion production rates of 2E13 per second are sufficient to constrain mixing angles as small as \sin^22θ=0.01 at 99% confidence level.

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arXiv2010

Exploring neutrino parameters with a beta-beam experiment from FNAL to DUSEL

We discuss in detail the physics reach of an experimental set-up where electron neutrinos (anti-neutrinos) produced in a beta-beam facility at Fermi National Accelerator Laboratory (FNAL) are sent, over a distance of L~1300km, to the Deep Underground Science and Engineering Laboratory (DUSEL). A 300kt Water Cherenkov (WC) detector and a 50kt Liquid Argon Time Projection Chamber (LArTPC) are considered as possible detector choices. We propose to use 18Ne and 6He as source ions for electron neutrino and electron anti-neutrino beams, respectively. The maximum Lorentz boost factor, gamma, available for these ions using the Tevatron are gamma_Ne=585 and gamma_He=350. This particular set-up provides the opportunity to probe the first oscillation maximum using the neutrino beam and the second oscillation maximum using the anti-neutrino beam which helps to evade some parameter degeneracies. The resulting physics sensitivities for theta_13, CP violation and the mass hierarchy are compared to those of a conventional superbeam from FNAL to DUSEL.

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arXiv2009

Some aspects of neutrino mixing and oscillations

Neutrino physics is now poised to move into the precision regime. Active attempts are under way to commence the era of precision neutrino measurement science which will surely widen the horizon of our knowledge about neutrinos. A number of high-precision neutrino oscillation experiments have been contrived to sharpen our understanding about these tiny particles. This is the right time to ask how different planned/proposed next generation experiments in the coming decades would perform to explicate the nature of neutrinos and our thrust for new physics. This thesis is an effort to have a look on several aspects of these issues.

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arXiv2008

CERN-INO magical Beta-beam experiment: A high precision probe for neutrino parameters

This talk is an attempt to underscore in detail the physics reach of an experimental set-up where neutrinos produced in a beta-beam facility at CERN would be observed in the proposed large magnetized iron calorimeter detector (ICAL) at the India-based Neutrino Observatory (INO). The "magical" CERN-INO beta-beam set-up offers an excellent avenue to use the "Golden" channel ($ν_e \to ν_μ$) oscillation probability for a simultaneous determination of the neutrino mass ordering and $θ_{13}$ avoiding the impact of the CP phase $δ_{CP}$ on these measurements. With Lorentz boost $γ=650$ and irrespective of the true value of $δ_{CP}$, the neutrino mass hierarchy could be determined at $3σ$ C.L. if $\sin^22θ_{13}{\rm {(true)}} > 5.6 \times 10^{-4}$ and we can expect an unambiguous signal for $θ_{13}$ at $3σ$ C.L. if $\sin^22θ_{13}{\rm {(true)}} > 5.1 \times 10^{-4}$ independent of the true neutrino mass hierarchy.

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arXiv2008

Probing neutrino parameters with a Two-Baseline Beta-beam set-up

We discuss the prospects of exploring the neutrino mass parameters with a CERN based Beta-beam experiment using two different detectors at two different baselines. The proposed set-up consists of a 50 kton iron calorimeter (ICAL) at a baseline of around 7150 km which is roughly the magic baseline, e.g., ICAL@INO, and a 50 kton Totally Active Scintillator Detector at a distance of 730 km, e.g., at Gran Sasso. We take 8B and 8Li source ions with a boost factor $γ$ of 650 for the magic baseline while for the closer detector we consider 18Ne and 6He ions with a range of Lorentz boosts. We find that the locations of the two detectors complement each other leading to an exceptional high sensitivity. With $γ=650$ for 8B/8Li and $γ=575$ for 18Ne/6He and total luminosity corresponding to $5\times (1.1\times 10^{19})$ and $5\times (2.9\times 10^{19})$ useful ion decays in neutrino and antineutrino modes respectively, we find that the two-detector set-up can probe maximal CP violation and establish the neutrino mass ordering if $\sin^22θ_{13}$ is $1.8 \times 10^{-5}$ and $4.6 \times 10^{-5}$, respectively, or more. The sensitivity reach for $\sin^22θ_{13}$ itself is $5.3 \times 10^{-5}$. CP violation can be discovered for 64% of the possible $δ_{CP}$ values for $\sin^22θ_{13} \geq 8\times 10^{-5}$.

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arXiv2008

Exceptional Sensitivity to Neutrino Parameters with a Two Baseline Beta-Beam Set-up

We examine the reach of a Beta-beam experiment with two detectors at carefully chosen baselines for exploring neutrino mass parameters. Locating the source at CERN, the two detectors and baselines are: (a) a 50 kton iron calorimeter (ICAL) at a baseline of around 7150 km which is roughly the magic baseline, e.g., ICAL@INO, and (b) a 50 kton Totally Active Scintillator Detector at a distance of 730 km, e.g., at Gran Sasso. We choose 8B/8Li source ions with a boost factor γof 650 for the magic baseline while for the closer detector we consider 18Ne/6He ions with a range of Lorentz boosts. We find that the locations of the two detectors complement each other leading to an exceptional high sensitivity. With γ=650 for 8B/8Li and γ=575 for 18Ne/6He and total luminosity corresponding to 5\times (1.1 \times 10^{18}) and 5\times (2.9\times 10^{18}) useful ion decays in neutrino and antineutrino modes respectively, we find that our two detector set-up can probe maximal CP violation and establish the neutrino mass ordering if \sin^22θ_{13} is 1.4\times 10^{-4} and 2.7\times 10^{-4}, respectively, or more. The sensitivity reach for \sin^22θ_{13} itself is 5.5 \times 10^{-4}. With a factor of 10 higher luminosity, the corresponding \sin^22θ_{13} reach of this set-up would be 1.8\times 10^{-5}, 4.6\times 10^{-5} and 5.3\times 10^{-5} respectively for the above three performance indicators. CP violation can be discovered for 64% of the possible δ_{CP} values for \sin^22θ_{13} \geq 10^{-3} (\geq 8\times 10^{-5}), for the standard luminosity (10 times enhanced luminosity). Comparable physics performance can be achieved in a set-up where data from CERN to INO@ICAL is combined with that from CERN to the Boulby mine in United Kingdom, a baseline of 1050 km.

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arXiv2008

Optimizing the greenfield Beta-beam

We perform a comprehensive and detailed comparison of the physics reach of Beta-beam neutrino experiments between two pairs of plausible source ions, (8B, 8Li) and (18Ne, 6He). We study the optimal choices for the baseline, boost factor, and luminosity. We take a 50 kton iron calorimeter, a la ICAL@INO, as the far detector. We follow two complementary approaches for our study: (i) Fixing the number of useful ion decays and boost factor of the beam, and optimizing for the sensitivity reach between the two pairs of ions as a function of the baseline. (ii) Matching the shape of the spectrum between the two pairs of ions, and studying the requirements for baseline, boost factor, and luminosity. We find that for each pair of ions there are two baselines with very good sensitivity reaches: a short baseline with $L [km]/ γ\simeq 2.6$ (8B+8Li) and $L [km]/γ\simeq 0.8$ (18Ne+6He), and a long ``magic'' baseline. For $γ\sim 500$, one would optimally use 18Ne and 6He at the short baseline for CP violation, 8B and 8Li at the magic baseline for the mass hierarchy, and either 18Ne and 6He at the short baseline or 8B and 8Li at the magic baseline for the $\sin^22θ_{13}$ discovery.

hep-ex↗

arXiv2008

Unraveling neutrino parameters with a magical beta-beam experiment at INO

We expound in detail the physics reach of an experimental set-up in which the proposed large magnetized iron detector at the India-based Neutrino Observatory (INO) would serve as the far detector for a so-called beta-beam. If this pure $\nue$ and/or $\anue$ beam is shot from some source location like CERN such that the source-detector distance $L \simeq 7500$ km, the impact of the CP phase $δ_{CP}$ on the oscillation probability and associated parameter correlation and degeneracies are almost negligible. This ``magical'' beta-beam experiment would have unprecedented sensitivity to the neutrino mass hierarchy and $θ_{13}$, two of the missing ingredients needed for our understanding of the neutrino sector. With Lorentz boost $γ=650$ and irrespective of the true value of $δ_{CP}$, the neutrino mass hierarchy could be determined at $3σ$ C.L. if $\sin^22θ_{13}{\rm {(true)}} > 5.6 \times 10^{-4}$ and we can expect an unambiguous signal for $θ_{13}$ at $3σ$ C.L. if $\sin^22θ_{13}{\rm {(true)}} > 5.1 \times 10^{-4}$ independent of the true neutrino mass hierarchy.

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arXiv2007

Physics with Beta-Beam

A Beta-beam would be a high intensity source of pure $ν_e$ and/or $\barν_e$ flux with known spectrum, ideal for precision measurements. Myriad of possible set-ups with suitable choices of baselines, detectors and the beta-beam neutrino source with desired energies have been put forth in the literature. In this talk we present a comparitive discussion of the physics reach of a few such experimental set-ups.

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arXiv2007

Magic Baseline Beta Beam

We study the physics reach of an experiment where neutrinos produced in a beta-beam facility at CERN are observed in a large magnetized iron calorimeter (ICAL) at the India-based Neutrino Observatory (INO). The CERN-INO distance is close to the so-called "magic" baseline which helps evade some of the parameter degeneracies and allows for a better measurement of the neutrino mass hierarchy and $θ_{13}$.

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arXiv2007

Neutrino parameters from matter effects in $P_{ee}$ at long baselines

We show that the earth matter effects in the ${\rm {ν_e \to ν_e}}$ survival probability can be used to cleanly determine the third leptonic mixing angle $θ_{13}$ and the sign of the atmospheric neutrino mass squared difference, $Δm^2_{31}$, using a $β$-beam as a $ν_e$ source.

hep-ph↗

arXiv2007

Probing Lepton Number Violating Interactions with Beta-beams

We show that a detector placed near a beta-beam storage ring can probe lepton number violating interactions, as predicted by supersymmetric theories with R-parity non-conservation. In the presence of such interactions, nu_tau can be produced during beta-decay leading to tau leptons through weak interactions. Alternatively, electron neutrinos from beta-decay of radioactive ions can produce tau leptons in a nearby detector through these interactions. The muons from the decay of these tau leptons can be readily identified in a small iron calorimeter detector and will signal violation of R-parity.

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arXiv2007

Neutrino mass hierarchy and $θ_{13}$ with a magic baseline beta-beam experiment

We underscore the physics advantage of an experiment where neutrinos produced in a beta-beam facility at CERN are observed in a large magnetized iron calorimeter (ICAL) at the India-based Neutrino Observatory (INO). The CERN-INO distance is close to the so-called "magic" baseline which helps evade some of the parameter degeneracies and allows for a better measurement of the neutrino mass hierarchy and $θ_{13}$. We expound the possibility of using radioactive $^8B$ and $^{8}Li$ as the source isotopes for the $\nue$ and $\anue$ beta-beam, respectively, and show that very good sensitivity to both the mass hierarchy and $θ_{13}$ is possible with a boost $γ$ in the 250-500 ballpark.

hep-ph↗

arXiv2006

Can R-parity violating supersymmetry be seen in long baseline beta-beam experiments?

Long baseline oscillation experiments may well emerge as test beds for neutrino interactions as are present in R-parity violating supersymmetry. We show that flavour diagonal (FDNC) and flavour changing (FCNC) neutral currents arising therefrom prominently impact a neutrino $β$-beam experiment with the source at CERN and the detector at the proposed India-based Neutrino Observatory. These interactions may preclude any improvement of the present limit on $θ_{13}$ and cloud the hierarchy determination unless the upper bounds on ${\not R}$ couplings, particularly $λ^{\prime}$, become significantly tighter. If ${\not R}$ interactions are independently established then from the event rate a lower bound on $θ_{13}$ may be set. We show that there is scope to see a clear signal of non-standard FCNC and FDNC interactions, particularly in the inverted hierarchy scenario and also sometimes for the normal hierarchy. In favourable cases, it may be possible to set lower and upper bounds on $λ^{\prime}$ couplings. FCNC and FDNC interactions due to $λ$ type ${\not R}$ couplings are unimportant.

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arXiv2005

Exploration prospects of a long baseline Beta Beam neutrino experiment with an iron calorimeter detector

A high intensity source of a single neutrino flavour with known spectrum is most desirable for precision measurements, the consensus direction for the future. The beta beam is an especially suitable option for this. We discuss the prospects of a very long baseline beta beam experiment with a magnetized iron calorimeter detector. In particular, with the source at CERN and the detector at the proposed India-based Neutrino Observatory (INO) the baseline is near the `magic' value where the effect of the CP phase is small. We observe that this experiment will be well suited to determine the sign of $m_3^2 - m_2^2$ and will be capable of probing $θ_{13}$ down to about 1$^\circ$.

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