We analyze very deep IRAC and MIPS photometry of \sim 12 , 500 members of the 14 Myr old Double Cluster , h and \chi Persei , building upon on our earlier , shallower Spitzer Cycle 1 studies ( Currie et al .
2007 , Currie et al .
2008 ) .
Numerous likely members show infrared ( IR ) excesses at 8 \mu m and 24 \mu m indicative of circumstellar dust .
The frequency of stars with 8 \mu m excess is at least 2 % for our entire sample , slightly lower ( higher ) for B/A stars ( later type , lower-mass stars ) .
Optical spectroscopy also identifies gas in about 2 % of systems but with no clear trend between the presence of dust and gas .
Spectral energy distribution ( SED ) modeling of 18 sources with detections at optical wavelengths through MIPS 24 \mu m reveals a diverse set of disk evolutionary states , including a high fraction of transitional disks , although similar data for all disk-bearing members would provide constraints .
Using Monte Carlo simulations , we combine our results with those for other young clusters to study the global evolution of dust/gas disks .
For nominal cluster ages , the e-folding times ( \tau _ { 0 } ) for the frequency of warm dust and gas are 2.75 Myr and 1.75 Myr respectively .
Assuming a revised set of ages for some clusters ( e.g . 7 ) , these timescales increase to 5.75 and 3.75 Myr , respectively , implying a significantly longer typical protoplanetary disk lifetime than previously thought .
In both cases the transitional disk duration , averaged over multiple evolutionary pathways , is \approx 1 Myr .
Finally , 24 \mu m excess frequencies for 4–6 M _ { \odot } stars appear lower than for 1–2.5 M _ { \odot } stars in other 10–30 Myr old clusters .