Re: Will the mini black hole be bigger or smaller then the ones forming now?

Thank you for your question. Its not certain if microscopic black holes 
are even possible. General Relatively would seem to permit black holes of 
any size, provided they can somehow achieve the matter/energy density 
required. It is the energy of the collision that determines whether or 
not a microscopic black hole could form. An experiment at CERN's Large 
Hadron Collider (LHC) in a year or so, will look for the signature of the 
decay of a microscopic black hole created by the upgraded proton-proton 
collider, namely Hawking Radiation.  

Quantum Black holes - SciAm article


Black Hole Search - LHC

The energy required is at least TeV (1,000,000,000,000 electron Volts). 
CERNs massive LHC rings (27 km circumference) may finally allow one to 
see the birth and decay of the theoretically postulated microscopic black 
hole. 

If it is possible to create a microscopic black hole at these energies, 
it would likely mean microscopic black holes have been "raining" on earth 
for billions of years. Cosmic rays span a considerable range of energies, 
but can attain the energies required to theoretically create a black 
hole. To date, no observation of Hawking radiation or a microscopic black 
hole has been made however.

Does it matter what the cosmic ray hits? Not from a practical 
perspective. The difference between Air and Uranium is the number of 
protons and neutrons. The energy of the collision is what is important. 
The cosmic ray may have more opportunities to collide in denser matter, 
but the energy of the collision is what is key. When the cosmic ray hits 
the proton or neutron of the nucleus, it will likely scatter. But the 
maximum energy available to the collision is the energy of the cosmic ray 
itself. The fraction of energy used in the collision will determine 
whether a micro-black hole could form. And once created, a micro-black 
hole will evaporate in a fraction of a second - giving a burst of Hawking 
radiation, at least according to the theory.