custom scoring

[ltomuno]

the following message comes from  Explanation explain
  0.09375  = (MATCH) fieldWeight(name:85 in 8687), product of
    1.0 = tf(termFreq(name:85)=1)
    1.0 = idf(docFreq=1406, maxDocs=14129)
    0.09375 = fieldNorm(field=name, doc=8687)


fieldNorm 0.09375 
the value 0.09375 is what determines and where can control it?
use 0.1 boost on the name field 
use CustomSimilarity
    public float computeNorm(String field, FieldInvertState state) {
        return state.getBoost();
    }
    public float queryNorm(float sumOfSquaredWeights) {
        return 1F;
    }
    public float tf(float freq) {
        return (float) 1F;
    }
    public float sloppyFreq(int distance) {
        return 1F;
    }
    public float idf(int docFreq, int numDocs) {
        return 1F;
    }
    public float coord(int overlap, int maxOverlap) {
        return 1F;
    }


thanks