Cosmic radiation induced backgrounds for low-background experiments    I.Abt, May 2023
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Consider Ge 0nubb and crystral based Dark Matter searches

                     0vubb                          DM
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 relevant energy     2 MeV (Ge) MeV range        keV range (crystal searches)
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 surface:
 before deployment   60Co (5.3y) 68Ge (270d)    65 Zn (244d) 68Ge (270d)  Tr (12.3y) 
 in germanium     enriched in 76Ge           natural               beta       beta
 atoms/kg/day pred   2.6         23             79           190          53 
 no shield arxiv:1706.0532
 other pred/data vary by factor or 2~3               
 doi:10.1088/1742-6596/1342/1/012089	       106+13        >71          82+-21
 
 in copper	     60Co from 63Co+n --> 60Co + alpha   peak x-section 13 MeV
 atoms/kg/day        86 +-8   
 PNNL-21696/Laubenstein+Heusser      

 ==> cut down surface exposure and try to shield and wait.
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in general: to create something close by (far away) from original element
            you need a slow neutron (a process destroying the original nucleus)
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underground:

high energy MUONS   Everything that happens above ground can happen 
create showers      down at the experiment depending on the rate of
with gammas         muons.
and neutrons        Muon vetos detect muons in the close vicinity.
                    But showers can come from the walls of laboratories.
		    In addition there are metastable/radioactive states that might
		    decay days/months/years/later

==> go down as deep as you can --> see flux in underground_flux_cpc....

Tritium             special case 14N + n --> 12C + Tr   stratosphere wandering down,
                    nasty background for DM searches    3.5kg Tritium in Biosphere
                    18.5keV negligible for 0vubb        99% in upper ocean layers
                    can also be created in direct pN interactions

==> think about LN shields for DM searches.

Everything else     No data base contains all metastable states of all elements.
                    No data base knows about all contaminations of all materials.

--------------------------0vubb----------------------------DM--------------------

NEUTRINOS           solar neutrinos extend to 8 MeV     known as the neutrino floor
                    they could create via CC a 2 MeV e  to be reached in next
                    [% level of LEGEND bckgr.budget]	generation experiments
                    NC vu e --> vu e can create 	mostly solar neutrinos
                    electron [all low E neutrinos]
		    vu[high E] N --> showers like muons
                    Might be negligible but
		    do not know 
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DM                  If it scatters only on              If a detector looks for     
0nubb               electrons? Like neutrinos,          0nubb it is automatically
		    if it leaves a 2 MeV recoil         affected 2nubb.
		    in a detector, which cannot         [not cosmogenic]
		    distinguish recoils from electrons
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