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