Alpha, Beta, Gamma Probe (GM) for rapid checking of laboratory bench and equipment surfaces and for checkout of personnel, the P-15 uses a 1-3/4” mica window diameter, 1.5 mg/cm2 pancake tube. Background is normally 50 to 60 counts per minute. Extremely sensitive to , and alphas with sufficient energy to penetrate window (Betas > 50 KeV). Window is protected by a 79% open, grill to prevent puncture or other damage while presenting minimum absorption to incoming radiation. Detects 5 KeV X-Rays and above.