An exploding primordial black-hole ( PBH ) may produce a single pulse of electromagnetic radiation detectable at the low-frequency end of the radio spectrum .
Furthermore , a radio transient from an exploding PBH could be a signature of an extra spatial dimension .
We describe here an approach for searching for PBH explosions using a low-frequency radio antenna array , and as a practical example , the results of a such a search using the Eight-meter-wavelength Transient Array ( ETA ) .
No compelling astrophysical signal was detected in \approx 4 hours of data implying an observational upper limit on the rate of exploding PBHs is 4.2 \times 10 ^ { -7 } pc ^ { -3 } yr ^ { -1 } for an exploding PBH with a fireball Lorentz factor of 10 ^ { 4.5 } for the standard scenario of Page and Hawking .
This rate limit is the strongest constraint yet set for PBH explosions with this fireball Lorentz factor .
Observations ( \sim 300 hours ) using the Arecibo Observatory were used to set a stronger constraint on the rate of PBH explosions for a fireball Lorentz factor of 10 ^ { 4.6 } but the limit set by those observations for the fireball Lorentz factor considered here are less stringent by more than an order of magnitude .
The limits considered here are applicable to exploding PBHs in the halo of the Galaxy .
These observations also imply an upper limit of 2.0 \times 10 ^ { -4 } pc ^ { -3 } yr ^ { -1 } on the rate of PBH explosions in the context of certain extra dimension models as described by Kavic et al .
This rate limit is for a fireball Lorentz factor of 10 ^ { 4.3 } which corresponds to an extra dimension compactification scale of 3.0 \times 10 ^ { -18 } m .