He stopping power and straggle in Al, Ti, Co, Cu, Ag, Ta and Au from 1.5 to 4Â MeV

He stopping power and straggle were measured in Al, Ti, Co, Cu, Ag, Ta and Au between 1.5 and 4 MeV. Measurements were made in an RBS geometry. Target thickness was measured by RBS relative to a NIST standard. Energy spectra were recorded using the Albany high resolution magnetic spectrometer. SRIM is generally in good agreement with measured stopping, the rms deviation between SRIM and experiment is 1.6% at 4 MeV. Straggle is much less than the Bohr estimate in high Z targets at low energy but approaches Bohr for the low Z targets at 4 MeV. Chu's calculated straggle are in better agreement with experiment, but generally predict straggle that is smaller than measured.