; INT Home
Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out
Your Federal Quarterly Tax Payments are due April 15th Get Help Now >>

INT Home

VIEWS: 4 PAGES: 8

  • pg 1
									Can the CNB be detected by a torsion balance?
              B. Heckel, Univ. of Washington
                                                                U
  vacuum can                      prehanger
                                                         
                                     HH coils
                                                                
      fiber
                                                       10 eV

autocollimator
           ()
                                       compensation
  thermal
                                          masses
   shield
                                        magnetic
pendulum                                shielding




    feet         turntable ()
                  ~ q   q   r /  
                          ~      ~
 V (r )  VN (r )1       e
                 
                                        
                                        
                         1    2  




~
q  BL
Can the CNB be detected by a torsion balance?
                          Hagmann, astro-ph/9902102
                          Ringwald, arXiv:0901.1529
                          Stodolsky, MPI-PAE/PTh 1/90
                          Braginsky, Klapdov, et al,




                                   , 

         F   f p

                                                        4
                          Relic Neutrinos

T= 1.95 K           <n> = 56 / cm3            N= S n = 300 /cm3


p = 5 x 10-4 eV ; at least 2 species non-relativistic; assume all non-relativistic


Gravitational clustering provides a density enhancement of 1.5-20; assume 10


Isotropically distributed in galaxy; Earth’s motion has v/c = 10-3

 Flux = 300 x 10 x 10-3 c = 1011 /cm2-s




                      h / p  0.25 cm
                           F   f p
f  N v rel  1011 / cm 2  s

                                                            4    t
                                              2                       3
   G F m2 2                2 m 
     2
                   57
          N n  2 10 N n cm   
                         2
                                                       Nn      
    8                         eV                          3  2  mn

p  m v rel  h /   5 10 4 eV


          N                         103 c   t            N     
a  F mt   t             27
                        10 cm / s 
                                  2
                                                                   
          v rel                      v rel  10 g cm3   3000 cm3 



 Smaller by (v/c)2 for Majorana neutrinos ?
                                         N     mr a
          3 cm



                                     .03 1010 rad
                             a                      3 1014 cm / s 2
                                  mr     30g  3cm
                 30 g
                                                         ( a  10 27 cm / s 2 )



30 g        a  10 15 cm / s 2 is possible, but still too large by 1012

       If all of the neutrons in 30g target scattered neutrinos coherently,
       a would be 10-19 cm/s2

       If all of the neutrinos incident on the 30g target scattered
       coherently, a would be 10-16 cm/s2
                  Conclusions

The coherent scattering of relic neutrinos leads to a large
enhancement of the scattering cross section.

Current torsion balance test masses scatter roughly 1 relic
neutrino per second. But the momentum transfer is too small
to be observable.

I wouldn’t fund this experiment.

								
To top