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Neutrino Mystery Cache

Hidden : 2/17/2005
Difficulty:
5 out of 5
Terrain:
1.5 out of 5

Size: Size:   other (other)

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Geocache Description:

For me, the best "puzzle" caches are those with real-world problems. In that spirit, I present this simple exercise.


The neutrino is not located at the listed coordinates, but is within 3 miles of them. Determine its position from the information given below.

This neutrino-sized (well, OK, slightly larger) container is located at a special spot. Calculate its position and go sign its electroweak log!

The neutrino was a 25-GeV muon neutrino, created by an accelerator at CERN, at N 46 14.135, E 6 05.458. The neutrino source is 54 m underground; the ground level elevation is 426 m above mean sea level. The neutrino was emitted in this direction:

Az: 321.22792 degrees
El: -42.1629426 degrees.

The neutrino cache you seek is located at the spot where the neutrino exited the Earth.

Details and assumptions:

  • Directions are given in local geodetic coordinates.
  • Use WGS-84 and EGM-96.
  • Assume that gravitational equipotentials are parallel to the WGS-84 ellipsoid.
  • Take into account the rotation of the Earth!
  • Feel free to send me coordinates to verify.


By the way, there are real-world experiments sending neutrinos through the Earth, from CERN and Fermilab. Some poor grad student had to do exactly the same kind of calculations you are performing here for those experiments!

Additional Hints (Decrypt)

[puzzle] Arhgevabf tb va n fgenvtug yvar evtug guebhtu gur Rnegu. Ab culfvpf vf erdhverq sbe fbyivat guvf ceboyrz; vg vf ragveryl trbzrgevp! [cache]Ernpu hc naq bire.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)