Digitization Procedure

Consultant's Meeting on Benchmarking of Digitization Software (Vienna, 12-14 November 2012) made recommendations on digitization procedure for EXFOR compilation. Selected recommendations for EXFOR compilers are summarized below with materials for digitization practice. See the summary report of the meeting (INDC(NDS)-0629) for the full list of recommendations.

Recommendations to EXFOR compilers

• Ask for numerical data from the authors. Explain to the authors that the original numerical data from the authors are preferable than values digitized from images.
• Avoid adoption of digitized values when the original values are explicitly given in the article (e.g., incident energy, detection angle).
• Enlarge the image as much as possible when the image file is created and digitized. Utilise functions available on the software for this purpose (e.g., "magnifying glass").
• Digitize the beginning and end points of scales with special care to avoid systematic errors.
• Check the values of the beginning and end points (labels on scales) after digitization of the image.

Guideline for expression of digitized data in EXFOR

1. Keep consistency for the number of digits between the digitized values and uncertainties. For example,

     DATA
     EN         DATA       DATA-ERR
     MEV        MB         MB
      14.1       12.34      2.34
      14.3       12.3       2.3
      14.5        1.234E+01  0.234E+01
      14.6        1.23 E+01  0.23 E+01
      ...
     ENDDATA
     

2. Use the fixed and floating decimal point expression for the numbers digitized from linear and logarithmic scale, respectively. For example,

   12.345

   (a value digitized from linear scale)

   1.2345E+02

   (a value digitized from logarithmic scale)
3. Digitization accuracy may be given in the absolute unit (e.g., ADEG) or relative unit (e.g., PER-CENT) for the numbers digitized from linear and logarithmic scale, respectively. For example,

     COMMON
     ANG-ERR-D  ERR-DIG
     ADEG       PER-CENT
      0.12       1.2
     ENDCOMMON
     DATA
     ANG-CM     DATA       DATA-ERR
     ADEG       MB         MB
       5.67       3.456E+02  0.234E+02
      12.31       2.345E+02  0.123E+02
      ... 
     ENDDATA
     

4. Consider rounding of digitized values to integers if values are for atomic numbers, mass numbers etc., and digitized values are close to integers.

Materials for digitization exercise

• Figure images (pdf)
• Original numbers (pdf)
• Spread sheet (for performance evaluation, xls)