Quartz crystal resonator and quartz crystal resonator unit

A quartz crystal resonator unit comprising:

• a quartz crystal resonator that includes:
• an AT-cut quartz crystal blank that is plate-shaped and that is rectangular when viewed in a direction normal to a first main surface thereof;
• and
• a first outer electrode and a second outer electrode disposed on the first main surface of the AT-cut quartz crystal blank and arranged in a short-side direction in which short sides of the first main surface of the AT-cut quartz crystal blank extend;
• a plate-shaped substrate body having a second main surface;
• and
• a third outer electrode and a fourth outer electrode disposed on the second main surface of the substrate body, wherein the first outer electrode and the third outer electrode are fixed to each other via a first electroconductive adhesive, and the second outer electrode and the fourth outer electrode are fixed to each other via a second electroconductive adhesive,
• wherein long sides of the main surface of the AT-cut quartz crystal blank are substantially parallel to a Z′ axis of the AT-cut quartz crystal blank,
• wherein the short sides of the main surface of the AT-cut quartz crystal blank are substantially parallel to an X axis of the AT-cut quartz crystal blank,
• wherein a frequency of a main vibration of the AT-cut quartz crystal blank is in a range of 20.0 MHz to 60.0 MHz, and
• wherein 0.050≤P≤−0.0047×F+1.728, where P (mm) is a minimum distance between a first portion where the first electroconductive adhesive is in contact with the quartz crystal resonator and a second portion where the second electroconductive adhesive is in contact with the quartz crystal resonator in the short-side direction, and F (MHz) is the frequency of the main vibration of the AT-cut quartz crystal blank.