Context : The Herschel Open Time Key Programme TNOs are Cool : A survey of the trans-Neptunian region aims to derive physical and thermal properties for a set of \sim 140 Centaurs and Trans-Neptunian Objects ( TNOs ) , including resonant , classical , detached and scattered disk objects .
One goal of the project is to determine albedo and size distributions for specific classes and the overall population of TNOs .

Aims : We present Herschel PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling .
We analyze our results for correlations , draw conclusions on the Plutino size distribution , and compare to earlier results .

Methods : Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods .
In order to improve the quality of our results , we combine our PACS data with existing Spitzer MIPS data where possible , and refine existing absolute magnitudes for the targets .
The physical characterization of our sample is done using a thermal model .
Uncertainties of the physical parameters are derived using customized Monte Carlo methods .
The correlation analysis is performed using a bootstrap Spearman rank analysis .

Results : We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28 .
The average albedo of the sample is 0.08 \pm 0.03 , which is comparable to the mean albedo of Centaurs , Jupiter Family comets and other Trans-Neptunian Objects .
We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120–400 km and q = 3 at larger sizes .
We revise the bulk density of 1999 TC36 and find \varrho = 0.64 _ { -0.11 } ^ { +0.15 } \mbox { g cm } ^ { -3 } .
On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo .
Furthermore , we find biases based on geometrical aspects and color in our sample .
There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample .

Conclusions :