1. REVIEW OF ESTIMATES OF RANDOM COMPONENTS IN THE INNER TRIPLET
HI LUMI and LARP collaboration meeting
CERN, 7th June 2012
REVIEW OF ESTIMATES OF RANDOM COMPONENTS IN THE INNER TRIPLET
E. Todesco
CERN, Geneva Switzerland
Based on the Phase-I work by F. Borgnolutti, P. Fessia,
on HQ estimates by X. Wang,
and tracking presented by Y. Cai in LARP CM May 2012

2. METHODS Random movements of coil blocks due to tolerances Note:
Amplitudes of the order of to 0.1 mm - Rref=40 mm
Estimate given for the Phase I [P. Fessia, et al., SLHC PR 45 (2010) IEEE Trans. Appl. Supercond. 20 (2010) 140 ]
Note:
Random b6 estimated with 4 times larger movements, based on experience
Uncertainty=random with exception of a6 and b6
This is the best estimate we have today

3. METHODS
Extrapolation to higher orders
Scaling with Biot Savart

4. and HQ measurements (spread along the axis)
METHODS
Comaprison with HQ estimates
Calculation by X. Wang on HQ cross-section, mm standard deviation of movements
Very similar results
Also in this case we take 4 times larger movement for b6
Measurements are not so far from this estimate
Comparison between estimates with s=25 mm movement (solid line)
and HQ measurements (spread along the axis)

5. DEPENDENCE ON AMPLITUDE
For a fixed aperture radius and Rref= 2/3 of the aperture, random components scale with inverse of aperture
This is due to the hypothesis that tolerances do not increase with larger aperture – i.e., they are absolute and not relative
Hypothesis suggested by analysis of built magnets [B. Bellesia et al, Phys. Rev. STAB 10 (2007) ]
Therefore for the 150 mm we assume a reduction of 20%

6. COMPARISON WITH WHAT PRESENTED IN LAST LARP CM
Random components of a6 and a10 look pretty pessimist
Other components (b4, b6) very optimist

7. COMPARISON WITH WHAT PRESENTED IN LAST LARP CM
Random components of a6 and a10 look pretty pessimist
They looked critical in Cai presentation
We suggest to have a second run with these new tables
Some dependence of random on the specific cross-section (up to 50%) – I would assume the same as MQXC for the moment

8. CONCLUSION First version of error tables
We always give errors at 2/3 of reference radius
I propose to just take phase I estimates and scale with inverse of the aperture