docs: def _get_asym_alpha_tag(self,a,b):
          """
              Find asymmetry from cryo oven with alpha detectors. 
              a: list of alpha detector histograms (each helicity)  
              b: list of beta  detector histograms (each helicity)  1+ 1- 2+ 2-
          """
  
          # beta in coincidence with alpha
          coin = a[:4]
          
          # beta coincidence with no alpha
          no_coin = a[4:8]
  
          # get split helicity asym from 
          hel_coin =      self._get_asym_hel(coin)
          hel_no_coin =   self._get_asym_hel(no_coin)
          hel_reg =       self._get_asym_hel(b)
          
          # get combined helicities
          com_coin =      self._get_asym_comb(coin)
          com_no_coin =   self._get_asym_comb(no_coin)
          com_reg =       self._get_asym_comb(b)
  
          # make output
          return (hel_coin,hel_no_coin,hel_reg,com_coin,com_no_coin,com_reg)