The Fermi Large Area Telescope ( LAT ) has observed more than a hundred of gamma-ray pulsars , about one third of which are radio-quiet , i.e .
not detected at radio frequencies .
The most of radio-loud pulsars are detected by Fermi LAT by using the radio timing models , while the radio-quiet ones are discovered in a blind search .
The difference in the techniques introduces an observational selection bias and , consequently , the direct comparison of populations is complicated .
In order to produce an unbiased sample , we perform a blind search of gamma-ray pulsations using Fermi-LAT data alone .
No radio data or observations at optical or X-ray frequencies are involved in the search process .
We produce a gamma-ray selected catalog of 25 non-recycled gamma-ray pulsars found in a blind search , including 16 radio-quiet and 9 radio-loud pulsars .
This results in the direct measurement of the fraction of radio-quiet pulsars \varepsilon _ { RQ } = 64 \pm 10 \% , which is in agreement with the existing estimates from the population modeling in the outer magnetosphere model .
The Polar cap models are disfavored due to a lower expected fraction and the prediction of age dependence .
The age , gamma-ray energy flux , spin-down luminosity and sky location distributions of the radio-loud and radio-quiet pulsars from the catalog do not demonstrate any statistically significant difference .
The results indicate that the radio-quiet and radio-loud pulsars belong to one and the same population .
The catalog shows no evidence for the radio beam evolution .