splitting of primes in extension fields

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Call L the maximal real subfield of the cyclotomic field of order 148.

The field L has a quartic subfield — call it K.

I want to see how a prime ideal of K splits in the top field L.

I defined L and K as follows.

sage: C.<a> = CyclotomicField(148)
sage: g = a + a**-1
sage: L.<b> = NumberField(g.minpoly()) 
sage: subfields = L.subfields()
sage: K = subfields[3][0]
sage: K  
Number Field in b3 with defining polynomial x^4 - 37*x^2 + 333
sage: I=K.ideal(37)
sage: F=I.factor()
sage: (Fractional ideal (37, b3))^4
sage: P=list[F]
sage: P
(Fractional ideal (37, b3), 4)
sage: P1= P[0];P1
Fractional ideal (37, b3)

I would like to see how the prime ideal P1 of K factor in the top field L. I tried the following code.

sage: O = L.ring_of_integers()
sage: J = O.P1

But I got the error: No compatible natural embeddings found for Number Field in b with defining polynomial x^36 - 37x^34 + 629x^32 - 6512x^30 + 45880x^28 - 232841x^26 + 878787x^24 - 2510820x^22 + 5476185x^20 - 9126975x^18 + 11560835x^16 - 10994920x^14 + 7696444x^12 - 3848222x^10 + 1314610x^8 - 286824x^6 + 35853x^4 - 2109x^2 + 37 and Number Field in b3 with defining polynomial x^4 - 37x^2 + 333

Could you please help me with this? Thank you.