Beam Loss Scintillators

This page contains information related to signal and machine induced background (MIB) analysis in Beam Loss Scintillators (BLS).

First estimates for the energy deposition profile for the nominal LHC operation at 7 TeV

-- VadimTalanov - 01-Dec-2009

Total profile

Using the calculated profile from p-p collisions one can assume:

• Bunch spacing of 25 ns

• Each bunch crossing gives event in IP

• Each event in IP gives BLS event

An example of the resulting energy profile in the BLS from the p-p collisions is then given below (blue - signal from event in IP, red - SUM).

In addition one can assume:

• Each colliding bunch loses one proton at TCTV on both Beam 1 and 2 and so will be accompanied by MIB

• Background from both beams gives BLS event

An example of total energy profile in the BLS including MIB is then given below (blue - signal from event in IP, green - MIB from Beam 1, cyan - MIB from Beam 2, red - SUM).

Collisions in IP8

100.000 events simulated with Gauss v37r5 options for MC09 and 7 TeV, and "sim-20090402-vc-md100" global tag. Spillover was manually switched OFF.

MIB at Beam 1

The MIB source was produced with 14×4600 = 64400 vertical halo losses simulated at TCTV on Beam 1

• This gave 15810 “filled” events (at the scoring plane of -2.1m from IP) or 25% (effect of layout and shielding)

• With Gauss we have 2213400 events simulated

• This gave 47002 events with ≥1 track in BLS ("BLS events") or 2.1% (per filled event)

Comparing to MIB at Beam 2, losses at TCTV on Beam 1 have ~6 times less chances to give a "BLS event".

For MIB at both Beam 1 and 2 there are long tails of signal arriving 10…20 ns after the first “wave” of background.

Definitely not enough initial halo losses simulated to recognize clearly the effect.

MIB at Beam 2

The MIB source was produced with 99×32 = 3168 losses vertical halo simulated at TCTV on Beam 2

• This gave 2567 “filled” events (at the scoring plane +19.9m from IP) or 81% (19% smeared inside LSS)

• With Gauss we have 154020 events simulated

• This gave 6047 events with ≥1 track in BLS ("BLS events") or 3.9% (per filled event)