Help understanding the behavior of an RLC circuit
In your simulation the values are somewhat independent, since you control switch ramp time dt=11us. in the model .

The L/R =T= 1.5uH/0.6 = 2.5us would be dominant if it had a &lt;1us time switch.

Fall time is usually calculated from 90 to 10% , which is longer than PW50  which is longer than T(100-50%).

T2 is dominated by R1C2=0.6*168uF= 100us.  Since 90-10%=80% , the T50% duration will be approx. 5/8*100us=63us, as a 1st approximation again determined by R1C2.

The zoomed simulation area needs more timebase resolution in your setup,as there is interpolation noise.  Unless you include stray capacitance on the switch and Rs for the capacitor and other factors, you can't expect more accuracy.

Is this an air core inductor? You might want to model the physical model for EMI stray effects with 16kA.!!