Our current best guess at Page 1  --  WORK IN PROGRESS

Page 1 is dynamically configured depending on the mode of the machine so the information available will vary.


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 Research, simplifcation and  graphics by Daniel Evans - Danny252


 Research, simplifcation and graphics by Daniel Evans - Danny252

The LHC state that is shown on page 1 is the mode that the LHC is currently in, i.e. which "master program" is controlling the components. There are a few of them, some are very automatic, some are needed for testing where manual adjustments are allowed by the operators.

Use the Definitations and Acronyms links on the left to decode the comments section

Good paper on Page 1 done by our great friend Markus Albert of CERN who provided us invaluable help on creating these pages

Detailed paper on Vistar displays



Fill: xzy => Integer number which increases usually every time  the LHC is run through its complete cycle.

E: xyz GeV => Energy derived from 4 of the 8 main bending circuits and distributed by the LHC timing system indicating at which energy level the LHC is set. It is provided by the energy tracking system and is not necessarily reflecting the LHC beam energy.

LHC Operating mode (example: “BEAM SETUP:CIRCULATE AND DUMP”) => concatenation of accelerator mode (before colon) and beam mode (after colon) (see also: https://edms.cern.ch/document/865811/1.1)

BCT TI2/8: Beam current transformers to measure the beam intensities downstream of the 2 transfer lines TI 2 and TI8 between SPS and LHC.

I(Bx): Slow beam current transformers in each of the two LHC rings to measure the whole beam intensity (including the uncaptured beam) of the circulating beam. The signal to noise ratio is rather bad for the currently low intensities of the order of up to 5E09 per bunch/beam.

SMP flags:

Setup Beam = The intensity limit threshold as a function of energy, below which the “SET-UP BEAM FLAG” becomes TRUE, was defined as the damage limit of Cu for transient beam loss based on simulation and experimental data.

Beam Presence = The BEAM PRESENCE FLAG is TRUE when there is circulating beam in the LHC, and FALSE if there is no circulating beam. There is one BEAM PRESENCE FLAG per beam.

Movable devices allowed in and Stable Beams = In general, the LHC beam modes are not used by machine protection devices. However to derive the flags “STABLE BEAM” and ”MOVING_IN_ALLOWED” it is required to know if the beam mode is either “STABLE BEAMS” or “UNSTABLE BEAMS”. The beam mode “STABLE BEAMS” is set by operations to indicate stable beams to the experiments, which is important before switching on certain detectors.

Setup Beam: It indicates somehow the damage potential of a beam, as it is based on the combination of beam intensity and beam energy. If for a given intensity the beam energy increases (during acceleration) the setup beam flag will transit at a given energy from TRUE to FALSE. It doesn’t indicate that the LHC is being prepared for the next beam.

PM Status B1 and PM Status B2 (at bottom corner): This status indicates for each beam if the post mortem system triggering is enabled. Under certain conditions operations disables the post mortem system triggering after a beam dump, i.e. when doing inject & dump studies.

BTVs: The 2 leftmost screens shown on your image are 2 of the 4 available injection BTVs for beam 1 (clockwise circulating beam) installed in point 2 of the LHC, whereas the 2 rightmost screens are 2 of the 4 available injection screens for beam 2 (anticlockwise circulating beam). Those BTVs (as well as others installed in the LHC ring and transfer lines between the SPS and LHC) can be put in beam using different screen materials. There are screens with a Cr doped AL2O3 luminescence plate (1mm thick) and Ti foils (12 μm thick).

BTV screens: They can be moved in beam (with different screen materials, Ti or Alumina) to acquire beam profiles or out of the beam path. The exact explanation of what you see on the image on your site is difficult, but it’s most likely not beam. Attached is a screenshot where you see dumped beam 2 on the two right side screens BTVD.623458.B2 and BTVDD.629339.B2 for beam 2. The beam spot is clearly visible.

Alumina screens are more sensitive and can observe single bunch beams of well below 10e9 particles. Ti-foil screens are less sensitive than Alumina screens and are usually used with higher intensity beams. The don’t perturb the beam and several of them can be inserted at the same time.

http://ab-dep-bi-pm.web.cern.ch/ab-dep- ... ies.BTVLHC

Operator comments: Text messages issued by the LHC operations team to communicate current problems, studies, activities etc. to the LHC experiments and the outside world.

CCC: CERN Control Center and the LHC landline phone numbers. The central control room at CERN was inaugurated in February 2006 and hosts all CERN accelerator operators together with the LHC cryogenics operations team and the operator surveying and controlling the technical infrastructure of CERN.

TI 2 - is the transfer line between the SPS and the LHC for the clockwise beam. It is 2943m long.
TI 8 - is the anticlockwise transfer line from the SPS to LHCand is 2694m long

TED - stands for 'Target External Dump' There are stoppers that can be put into the transfer lines there is one at the top and one at the bottom of each line (upstram and downstream) . Each one weighs about 20 tonnes.

TDI - this is an injection protection element just downstream of the injection point. It has upper and lower jaws that can be moved into the beamline. If the injection kickers fire correctly the beam will be fired through the gap between the jaws. If the kickers do not fire - for example when we are setting up injection - the beam hits one of the jaws and is absorbed.

BKG1,2,3 - These are figures of merit provided by the experiments to the machine. Each one is derived from a specific part of the detector (and are therefore experiment specific). They are normalized to a number between 1 (good) and 5 (bad) - 0 means it is not yet active.

This contains a nice explanation of luminosity and intensity... there's lots and lots of detail there.


roughly speaking,
intensity = number of particles in a bunch
luminosity = number of particles going through a cm^2 per second