Scientists operating the Large Hadron Collider atom smasher at the CERN nuclear research facility in Europe say they have put the "pedal to the metal," colliding particles at record-breaking energies.

The record for the most energetic collision ever achieved came in a May 20 test run of the particle accelerator following its restarting in April after a two-year hiatus for upgrades, the European Organization for Nuclear Research announced the following day.

"Last night, protons collided in the Large Hadron Collider (LHC) at the record-breaking energy of 13 TeV (teraelectronvolts) for the first time," CERN stated.

The previous record highest energy for collisions was 8 TeV, attained in 2012.

The upgrades performed on the LHC are intended to eventually provide energy levels of 14 TeV.

Before its two-year upgrade, the LHC has confirmed the existence of the Higgs boson, sometimes referred to as the "God particle," which gives mass to all other particles in the universe and is considered the underpinning of the Standard Model of physics.

The discovery led to the awarding of the 2013 Nobel Prize for physics to the scientists who in 1964 had proposed its existence.

With the successful attainment of 13 TeV in tests, a full roster of experimental runs at that energy level will begin in June, scientists say, to provide collision data for three experiments being run at the LHC, including ATLAS, ALAS and CMS.

A circular 17-mile underground tunnel houses the LHC, inside of which billions of protons are flung in opposite directions around at 99.9 percent of the speed of light, then smashed together to release a shower of particles picked up by the various experiments' detectors.

Scientists are hoping the new experiments will yield more insights into possible as-yet-undiscovered particles and forces that bind them to each other.

One theory that will be in the scientists' minds as they examine the particles the new high-energy collisions throw off is supersymmetry, which holds that for each known subatomic particle there is a companion "super particle" waiting to be discovered.

One goal of the current test runs is the setup and calibration of devices known as collimators designed to protect the machine and its sensitive detectors from particles that might escape from the edges of the tightly controlled main beam, CERN said.