Investigation of LHC orbit correction
By Harry Hagen
• We used the Timber application to inspect the variable: RB.A12- It’s a constant at the injection and collision times.- RB.A12 = 757.2. A at injection- RB.A12 = 5889.6 A at collision
• We only noted down the data if the collisions lasted at least 30 minutes. This is to ensure that we had good conditions in the machine.• We carefully selected the time intervals. We chose the range of days from the beginning of May to June 13.•To find the time of injection and collision, we used the graph to find the approximate area then used the Excel application to find a more accurate point for the times of injection and collision.
Investigation of collision during May 7th, 2010
Time of injection
Time of collision
Collision lasts longer than 30
minutes
In excel
Find the moment just before the constant 757.20
changes
This value is the time when the injection
ended
Now do the same thing to
find the collision value
Find the moment just as
the value becomes the
constant 5889.63
This is when the collision
beganLook around
2:30
Look around 3:20
How to find the time of collision and injection
Label the areas you want
• Now that we know the injection and collision times, we can select specific time intervals from which to extract data.• We will extract data from both V-Orbit corrections and H-Orbit corrections.• The time intervals will have a 10 minute range.• The time intervals which we will be using will be:
- (Time of injection – 10 minutes) to Time of injection- (Time of collision + 5 minutes) to ( Time of collision + 15 minutes)
Find ORBIT_H_CORRECTION
Select all variables
Extracting data
We query the variables
We select the time intervals for injection
We select a day when a collision took place
Then we query the information as an excel file
Now we select the time intervals for collision
And make another query for that file
We repeat this process for every day we found a successful collision that lasts longer than 30 minutes
We should save the data with consistent names
This would make data extraction an easier task later
Add and query all ORBIT_V_CORRECTION
variables
We repeat the same thing for V_CORECTIONS
Remove all ORBIT_H_CORRECTION
variables
We wrote the filenames of the data into a spreadsheet
And with the help of a macro, we crunched the
data together into one file
We named this file TIMBERcrunch
Using the AVERAGE function, we calculated the average current each
circuit produced
We plotted this as a graph
But we soon realized that there were special function circuits
Fortunately, we knew which circuits to filter from our graph
In the worksheet INJ-V-ORBITI (
A)
Circuit position
Using a worksheet titled LHC ref layout, we could identify which circuits belonged to a particular
sector.We added a new column in TIMBERcrunch to label
each circuit into their corresponding sector
Then using specific parameters, we could identify the special function circuits and remove them from
our results
The graph now looked like this
I (A)
Circuit position
INJ-V-ORBIT
Then we wanted to find the average current from all the circuits in a sector rather than the average current from a specific circuit.
I (A)
Sector
We repeated the same thing with:- COL-V-ORBIT- INJ-H-ORBIT- COL-H-ORBIT
INJ-V-ORBIT
Semi-conclusion: V-ORBIT must have a correlation
COL-H-ORBIT
Average by circuit
I (A)
Circuit position
Average by sector
COL-H-ORBIT
I (A)
Sector
Conclusion: No obvious correlation in H-ORBIT
Since V-Orbit seems to show a correlation, we decided to investigate it further
Sector Average (I) Theta1-2 0.32 -0.242-3 0.54 -0.413-4 0.74 -0.564-5 0.57 -0.435-6 0.36 -0.276-7 0.15 -0.127-8 -0.09 0.078-1 -0.06 0.05
Sector Average (I) Theta1-2 2.00 -0.192-3 3.80 -0.373-4 5.39 -0.524-5 4.51 -0.445-6 2.26 -0.226-7 0.88 -0.097-8 -0.62 0.068-1 -0.58 0.06
Injection Collision
Sector I COL/INJ1-2 6.3
2-3 7.0
3-4 7.3
4-5 7.9
5-6 6.3
6-7 5.8
7-8 7.1
8-1 9.5
It is interesting to note that dividing collision current by injection appears to give us a value very close to ( 3500/450 ) = 7.8
Imagine a cylinder representing the distance from the Earth’s surface to the centre of the Earth
“Earth surface”
Earth centre
θ
~ 5600 m
LHC ρ = 2804m ~= 2800m
r_earth ~= 6371 X 103 m
Tanθ = ρ
r_earth
r_ea
rth
θ ~= 0.44 mrad
g1 g2
r2r1
Conclusion: Very good correlation for V-ORBIT
COL-V-ORBIT
INJ-V
-OR
BIT
AppendixLSS
LSS
LSS
LSS
LSS
LSS
LSS
LSS
D_earth= 2x r_LHC + (0+1+2Cos(45°)LSSLSS = 2538 mGives R_LHC = 3453 m θ = 0.54 mrad
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