Chapter 5, Problem 8P

Q7. A Si sample is doped with 1016 cm-3 donor impurity is exposed by light at x = 0 to generate excess EHP of amount 1014/cm³. Excess carriers travel 1 cm distance in 0.4 ms time under a field of 2 V/cm. (a) Calculate p(x) and n(x) at x = 2Lp. (b) Calculate diffusion current density at x= 0, Lp, and 2Lp. (c) Calculate mobility for majority and minority carriers. [Dp = 25 cm²/sec, Dn = 50 cm²/sec, T₁ = Tp = 10 ns]

The 10-fold X-ray reduction values for (a) water, (b) concreate, (c) iron and (d) lead are equal 100 cm, 20 cm, 10 cm and 5 cm, respectively. Find corresponding values of linear attenuation coefficients. can you use the formulas in the pictures please.

In real recording situations there are multiple devices that each have their own sampling rate. An audio file's sample rate is determined by the set up's lowest quality (smallest) sampling rate. Examine these recording set ups and determine the Nyquist frequency of the resulting digital file: Set up 1: 1. A microphone with a sampling rate of 48,000HZ 2. An audio processor with a sampling rate of 41,000HZ 3. What is this set up's Nyquist Frequency: Set up 2: 1. A speaker with a sampling rate of 46,050HZ 2. A microphone with a sampling rate of 12,000HZ 3. What is this set up's Nyquist Frequency: Set up 3: 1. A speaker with a sampling rate of 4,000HZ 2. A microphone with a sampling rate of 48,000HZ 3. An audio processor with a sampling rate of 41,000HZ 4. What is this set up's Nyquist Frequency:

1. On a typical Atomic Absorption Spectrophotometer, what are the detection limits for iron? (i.e. What are the maximum and minimum concentrations that can be measured?) 2. What happens when the existing concentration of ions, substituted into a Ksp expression, exceeds the numerical value of Ksp?

What is the d-spacing of an XRD of a BCC crystal corresponding to a peak at 50ᵒ when studied using 1.5406 Aᵒ wavelength X-ray?. If a = 14.5316 Aᵒ for the crystal, what are the Miller indices corresponding to this peak?

Gamma-ray detectors like the one described in the preceding problem often use calorimetry to determine gamma-ray energies. Suppose a beam of 100-MeV gamma rays strikes a target with a mass of 2.5 kg and specifi c heat 430 J/(kg # K). How many gamma rays are needed to raise the target’s temperature by 10 mK?

A Perspex (Lucite) phantom is used to calibrate a 6 MV photon beam. A cylindrical air ion chamber has a wall thickness (polystyrene) of 0.20 g/cm2 and an inner diameter of 5 mm. The ion chamber is placed at a depth of 5 cm in the phantom. The NxAion = 1.05 × 1010 R/C (T = 22 oC, P = 760 torr) for Co-60 for this chamber. Charge collected is 2.50 × 10-8C at P = 750 torr and T = 20.0 oC. The ion collection efficiency is 0.985. (a) Calculate the Ngas (Gy/C) for the chamber. (b) Calculate the absorbed dose (Gy) in Perspex at this depth. (c) What would be the absorbed dose (Gy) in water at approximately the same depth in a water phantom?

A technique of 40 mAs , 200 kV, 200 cm SID produces 0.12 Gy exposure. If we change the technique to: 80mAs, 175 kV at 100 cm SID find the new exposure in rad?

if a record sample has rate of 44100Hz, how many samples are required to capture 0.25s?