“performance of btvs during the cngs commissioning” e. bravin ab/bi nbi 2006 6 th international...
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“Performance of BTVs during the CNGS commissioning”
E. Bravin AB/BI
NBI 2006
6th International workshop on Neutrino Beams and Instrumentation4-9 September 2006 - CERN - Geneva
E. Bravin AB/BI CERN - NBI 20065 September 2006 2
Beam TV Observation Systems (BTV) for CNGS
The devices are equipped with scintillating screens (Alumina) and/or OTR radiators (Titanium and Carbon)
There are two types of cameras: CCD (standard) and SYRA (radiation hard CMOS sensor)
2 BTVE in the SPS, one before and one after the extraction septa. (Alumina and Titanium + CCD)
3 BTV in LSS4 and TT40 (Alumina and Titanium + CCD)
6 BTVG in TT41 (Carbon and Titanium + CCD)
2 BTVG in the target area (Carbon and Titanium + SYRA)
E. Bravin AB/BI CERN - NBI 20065 September 2006 3
Images (OTR)
BTVG.411006BTVG.410406BTVG.410706 BTVG.411906 BTVG.412424
BTVG.412434BTVG.412445
BTVG.412108
Intensity ~ 1012 protons
BTVG.411006BTVG.410406BTVG.410706 BTVG.411906 BTVG.412424
BTVG.412434BTVG.412445
BTVG.412108
Intensity ~ 1013 protons
E. Bravin AB/BI CERN - NBI 20065 September 2006 4
Radiation
BTVI_TT40.4001051013 protonsSingle image
BTVI_TT40.4001051013 protons
Average of 20 images
E. Bravin AB/BI CERN - NBI 20065 September 2006 5
BTV
.410
406
BTV
.410
706
BTV
.411
006
BTV
.411
906
BTV
.412
424
BTV
.412
445
-1
-0.5
0
0.5
1
1.5
2
2.5
BTV
BPM
Po
siti
on
[m
m] Horizontal
BTV
.410
406
BTV
.410
706
BTV
.411
006
BTV
.411
906
BTV
.412
424
BTV
.412
445
-3-2.5
-2-1.5
-1-0.5
00.5
11.5
2
BTV
BPM
Po
siti
on
[m
m]
Vertical
TT41 BTVGBeam position
E. Bravin AB/BI CERN - NBI 20065 September 2006 6
TT41 BTVGBeam position
There is a considerable difference between the readings of the beam position monitors and the values calculated from the images.
It looks like the values from the BPMs are to be trusted
Investigations are ongoing in order to understand the discrepancy.
There must be a problem during the different stages of the survey and alignment procedure.
E. Bravin AB/BI CERN - NBI 20065 September 2006 7
BTV
.410
406
BTV
.410
706
BTV
.411
006
BTV
.411
906
BTV
.412
108
BTV
.412
424
BTV
.412
435
BTV
.412
445
0
0.2
0.4
0.6
0.8
1
1.2
1.4
s.y.opt
s.y.btv
Siz
e [m
m]
BTV.410
406
BTV.410
706
BTV.411
006
BTV.411
906
BTV.412
108
BTV.412
424
BTV.412
435
BTV.412
445
0
0.2
0.4
0.6
0.8
1
1.2
1.4
s.x.opt
s.x.btv
Siz
e [m
m]
Horizontal
Vertical
* = 5.5 mp/p= 1.5 10-4
* = 5.5 mp/p= 1.5 10-4
TT41 BTVGBeam Size
E. Bravin AB/BI CERN - NBI 20065 September 2006 8
TT41 BTVGBeam Size
In the horizontal plane the measured beam sizes agree rather well with the optics parameters calculated by MAD.
In the vertical plane this agreement is less good.
The last two cameras do not have sufficient resolution at the moment and the measured sizes are in fact just the bandpass of the instrument.
A problem in the alignment forced the adoption of a small magnification factor for the camera lenses of the last two devices. This will be corrected in the near future. In order to maximise the resolution the field of view will be reduced to ~25x25 mm2.
E. Bravin AB/BI CERN - NBI 20065 September 2006 9
Conclusions
The BTV systems have been successfully used for the commissioning of CNGS
A few issues remain to be solved: Alignment errors Resolution limit for the last two devices
Differences between measured values and MAD optics to be understood
Radiation damage to the cameras (especially last two devices) to be monitored