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Bus Tape Radiation Length. (Update following Carl’s e-mail). Old Table (>1yr). NB. This build-up gets the tape mass right but… Build from Carl’s e-mail kapton (25), copper (18), adhesive#1 (25), kapton (25), adhesive#2 (25), aluminium (50), adhesive#1 (25), kapton (25)
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Bus Tape Radiation Length (Update following Carl’s e-mail)
Old Table (>1yr) • NB. This build-up gets the tape mass right but… • Build from Carl’s e-mail • kapton (25), copper (18), adhesive#1 (25), kapton (25), adhesive#2 (25), • aluminium (50), adhesive#1 (25), kapton (25) • adhesive#1 = modified epoxy adhesive#2 = modified acrylic
Build Revisions • Bugs in my table • Copper thickness =0.025mm – should be 0.018mm • I had an extra glue layer filling voids between tracks • I missed out a glue layer between the aluminium screen and the cover layer • Fixing these I now get…
Revised table with correct build • Remaining issue is glue radiation length
Revised table with correct build and Carl’s glue X0 Conclude that difference is 0.164 – 0.146 = 0.018% Corresponds to 11% change
X0 Web Search • LBL ‘Pixel Detector’ • http://www.lbnl.leog.org/pixel_rad_length.pdf • 0.025mm adhesive at X0=350mm • GLAST • http://scipp.ucsc.edu/groups/glast/meeting/tech_meeting/20001011/GLAST_Tray_Material.pdf • 0.038mm at X0=300mm (K-glue) • G10 Insulator at X0=194mm, mentions kapton X0=286mm • Polyurethane (film … not an adhesive) • http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=62061 • C25H42N2O6 • Molecular weight 466.6g/mol • Density = 1.2g/cc • X0 = 34.6cm • Acrylic • C3H4O2 • Density = 1.05g/cc • X0 from formula and density = 37.2 • http://arxiv.org/ftp/physics/papers/9908/9908049.pdf references PDG booklet X0=34.5cm