X-ray mass attenuation coefficients Tables of X-Ray Mass Attenuation Coefficients National Institute for Standards and Technology website NIST tables Beim NIST X-ray mass attenuation coefficients NIST: X-Ray Mass Attenuation Coefficients NIST tables NIST: X-Ray Mass Attenuation Coefficients Tables of X-Ray Mass Attenuation Coefficients Beim NIST X-Ray Mass Attenuation Coefficients for Elements 1-92 National Institute for Standards and Technology website http://www.nist.gov/pml/data/xraycoef/index.cfm http://www.nist.gov/pml/data/xraycoef/index.cfm