Earth tomography with the ICAL detector at INO

Observing matter effects in atmospheric neutrinos traveling through the entire mantle and core of the Earth is a promising way of enhancing our understanding of Earth’s density structure. In that context we study the prospects of Earth tomography with the ICAL detector at the India-based Neutrino Observatory. While this experiment is smaller in size in comparison to some of the other larger detectors being proposed, it is the only planned neutrino experiment with charge-identification sensitivity. In particular, ICAL can see matter effects separately in neutrinos and antineutrinos. This has been seen to enhance ICAL’s sensitivity to earth matter effects and hence the mass ordering sensitivity for both normal and inverted mass orderings. It is therefore pertinent to see if the ICAL sensitivity to earth tomography is competitive or better with respect to other experiments, especially for the inverted mass ordering, where other experiments suffer reduced sensitivity. We present the sensitivity of ICAL to earth tomography by taking into consideration both the Earth’s mass constraint as well as the hydrostatic equilibrium constraints.

Figure 1

Panel (a) shows the change in density of mantle according to case I. Panel (b) shows the effect of density change on the survival probability via $\mathrm{\Delta }{P}_{{\nu }_{\mu }{\nu }_{\mu }}=P_{{\nu }_{\mu }{\nu }_{\mu }}^{PREM}-P_{{\nu }_{\mu }{\nu }_{\mu }}^{newPREM}$ for NO and neutrinos, where $newPREM$ corresponds to density modified case. Panel (c) is the same as panel (b) but for IO and antineutrinos.

Figure 2

The panels shown here are the same as in Fig. 1 but for density change in OC for case I.

Figure 3

Panel (a) shows the change in density of mantle according to case II. Panel (b) shows the effect of density change on the survival probability via $\mathrm{\Delta }{P}_{{\nu }_{\mu }{\nu }_{\mu }}=P_{{\nu }_{\mu }{\nu }_{\mu }}^{PREM}-P_{{\nu }_{\mu }{\nu }_{\mu }}^{newPREM}$ for NO and neutrinos, where $newPREM$ corresponds to density modified case. Panel (c) is the same as panel (b) but for IO and antineutrinos.

Figure 4

The panels shown here are the same as in Fig. 3 but for density change in OC for case II.

Figure 5

Panel (a) shows the change in density of mantle according to case III. Panel (b) shows the effect of density change on the survival probability via $\mathrm{\Delta }{P}_{{\nu }_{\mu }{\nu }_{\mu }}=P_{{\nu }_{\mu }{\nu }_{\mu }}^{PREM}-P_{{\nu }_{\mu }{\nu }_{\mu }}^{newPREM}$ for NO and neutrinos, where $newPREM$ corresponds to density modified case. Panel (c) is the same as panel (b) but for IO and antineutrinos.

Figure 6

The panels shown here are the same as in Fig. 1 but for density change in OC for case III.

Figure 7

The ${\chi }^2$ as a function of percentage change in density in the mantle for case I. Red lines are for NO and blue lines are for IO. Panel (a) is for ${\theta }_{23}=42°$, (b) for ${\theta }_{23}=45°$ and (c) for ${\theta }_{23}=49°$. Upper panels are for no systematic uncertainties in the analysis while the lower panels show the ${\chi }^2$ including systematic uncertainties.

Figure 8

Same as Fig. 7 but for percentage density change in OC.

Figure 9

The ${\chi }^2$ as a function of percentage change in density in the mantle for case II. Red lines are for NO and blue lines are for IO. Panel (a) is for ${\theta }_{23}=42°$ (b) for ${\theta }_{23}=45°$ and (c) for ${\theta }_{23}=49°$. Upper panels are for no systematic uncertainties in the analysis while the lower panels show the ${\chi }^2$ including systematic uncertainties. The shaded region shows the nonphysical density change when we use the hydrostatic equilibrium condition.

Figure 10

All panels show plots of $\chi 2$ as a function of percentage change in OC density for case II. Panel (a) is for ${\theta }_{23}=42°$, (b) for ${\theta }_{23}=45°$, and (c) for ${\theta }_{23}=49°$, both without (upper plots) and with (bottom plots) systematic uncertainties in the ${\chi }^2$ analysis. Blue lines are for NO and red lines are for IO. The shaded region shows the nonphysical density change when we use the hydrostatic equilibrium condition.

Figure 11

All three panels has plots for ${\chi }^2$ as a function of percentage change in density of mantle for case III (putting Earth mass constrain in inner layers). Where (a) is for ${\theta }_{23}=42°$ (b) for ${\theta }_{23}=45°$ and (c) for ${\theta }_{23}=49°$ without (upper plots) and with (bottom plots) systematic uncertainties in ${\chi }^2$ analysis.The blue line is for NO and red line for IO as a known MO case. The shaded region shows the nonphysical density change when we use the hydrostatic equilibrium condition.

Figure 12

All three panels has plots for ${\chi }^2$ as a function of percentage change in density of OC for case III (putting Earth mass constrain in inner layers). Where (a) is for ${\theta }_{23}=42°$ (b) for ${\theta }_{23}=45°$ and (c) for ${\theta }_{23}=49°$ without (upper plots) and with (bottom plots) systematic uncertainties in ${\chi }^2$ analysis.The blue line is for NO and red line for IO as a known MO case. The shaded region shows the nonphysical density change when we use the hydrostatic equilibrium condition.