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BE-BI-PM Section


TV Beam Observation System for LHC

Different types of BTV in LHC

In LHC several types of BTV systems will be installed. This multiplicity is due to the different needs and the different beam lines where they will be installed. The different types share large portions of design. One single control electronics is capable of dealing with all different systems. This simplifies the design and the operation.

BTVI
These systems are used in the transfer lines from the SPS to the LHC (TI2 and TI8). The system is composed of a four position rotative support that can accommodate two different radiators, the remaining two positions are kept empty and allow the free passage of the beam. These tanks have been designed at CERN and built at Dubna. The radiators consist of one chromium doped alumina screen, used for low beam intensities, and one OTR titanium foil used for higher intensities.
BTVSI
These are the ring types BTV. The system is composed of a linear actuator that holds two different radiators and a pass trough chamber. One of the radiators is a 1 mm thick alumina (Al2O3:Cr) slab and the other a thin (12μm) titanium foil. The pass trough chamber is designed such that when the system is in parking position (OUT) the beam does not see any discontinuity in the beam pipes and thus no additional impedence. These systems only intercept one of the two beams, the other will pass in an adiacent separate vacuum pipe.
BTVSS
This device is installed just after the septum and is used, together with two BTVSI, to verify that the injection trajectory is correct. The actuator is of linear type with three positions, two for radiators and one for free passage. As for all other BTV types installed in the ring the design is such to minimize discontinuities and impedence. The vacuum tank only contains one of the beams (either beam 1 or 2), the other is contained in a separate beam pipe near by. At this location be injected beem is still well separated from the its closed orbit, so the radiators do not intercept the circulating beam.
BTVST
This type of devices is used to monitor the beam being injected in LHC, it is located just before the TDI injection dump. As for the BTVSI these devices are equipped with a linear actuator with two positions for radiators and one for the free passage of the beam. The radiators are of the same type as well, i.e. an alumina screen and a titanium OTR foil. Care has been taken to reduce the discontinuities and thus the impedence when in OUT position. This device ha a large vacuum chamber that accomodates both beam (beam 1 and beam 2). At this position the injected beam is already on the closed orbit, if the injected beam is not immediatly sent to the beam dump it will be intercepted by th eradiator at each turn with the possibility of damaging it.
BTVSE
This device is used to monitor the beam being dumpedand is located downstream of the dump kickers. Again the type of the movement is linear with two radiators and one passage (same type of radiators). The vacuum chamber only contains one beam and the circulating beam is not intercepted by the radiators even when inserted.
BTVD
This device is used to monitor the beam being extracted from LHC and is located at the beginning of the dump line. Again the type of the movement is linear with two radiators and one passage (same type of radiators).
BTVDD
This device is used to monitor the beam being extracted from LHC and is located 30 meters upstream of th ebeam dump. It consists of a single large dimension fixed alumina screen (~60cm diameter). The main use of this screen is to observe the correct functioning of the dilution kickers. The screen is divided into 5 sectors: 4 quarter circle with a 5cm hole in the center and a central screen covering the hole. In case all dilution kickers fail only the central part of the screen gets destroyed, limiting the damage.

BTV equipments in the LHC ring and injection zones

OctantNameDevicePosition wrt IP1 (m)Beta [m]Dispersion [m]Beam size [mm]
   EntranceExitHVHVHV
IR2BTVSS. 6L2.B1cfv-ua23-btvinj#13139.81243140.5624130.070.2-0.19-0.011.010.74
 BTVSI.C5L2.B1cfv-ua23-btvinj#23168.84143169.3414180.522.8-0.25-0.021.180.42
 BTVSI.A5L2.B1cfv-ua23-btvinj#33186.67943187.179466.860.5-0.16-0.030.720.69
 BTVST.A4L2.B1cfv-ua23-btvinj#43246.62743247.2274102.446.3-0.080.000.890.60
IR3BTVM . 7L3.B2cfv-uj33-btvm#26424.61586425.115853.3115.50.940.080.640.95
 BTVM . 7L3.B1cfv-uj33-btvm#16444.35486444.8548144.686.22.250.041.060.82
IR4BTVM . 6L4.B1cfv-us45-btvm#19847.96129848.4612284.0306.0-0.170.051.491.54
 BTVM . 6L4.B2cfv-us45-btvm#29848.66129849.1612296.2329.80.250.051.521.60
IR7BTVSI.A7R7.B2cfv-uj76-btvm#120229.756420230.2564219.754.70.64-0.061.310.65
IR8BTVST. 4R8.B2cfv-ua87-btvinj#623400.435823400.935897.240.70.020.060.870.56
 BTVSI.A5R8.B2cfv-ua87-btvinj#523460.483823460.983862.869.1-0.090.050.700.73
 BTVSI.C5R8.B2cfv-ua87-btvinj#423478.328823478.8288155.339.2-0.140.011.100.55
 BTVSS. 6R8.B2cfv-ua87-btvinj#323507.100823507.8508124.887.7-0.12-0.040.980.83
TD68BTVSE.A4L6.B1cfv-us65-btvd#1163.625 475.0158.0  1.921.11
 BTVD.683458.B1cfv-us65-btvd#2347.777 475.0?158.0?  1.921.11
 BTVDD.689339.B1cfv-us65-btvd#3933.900 4626?3584?  6.005.28
TD62BTVSE.A4R6.B2cfv-us65-btvd#4163.625 152.3247.7  1.091.39
 BTVD.623458.B2cfv-us65-btvd#5345.777 479.0?158.9?  1.931.11
 BTVDD.629339.B2cfv-us65-btvd#6933.900 4662?3351?  6.02?5.11?

1)Optics V 6.500 (Updated on 26 July 2006)
2)Twiss parameters for IR4 are only indicative as these devices are not included in the Optics files
3)The following values have been used to compute beam sizes

ε*=3.50 10-6m
ε=7.78 10-9m
βγ=450 
ΔP/P=0.0 

(At 7 TeV the beam sizes in the extraction channel (BTVSE and BTVD) are of the order of 0.3mm)

Thermal load calculations for the LHC radiators


BTV sdds logging (SPS and LHC) is @ : /nfs/cs-ccr-nfs6/vol5/u1/slops/data/SDDS-LOGGING/


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Page last modified on February 19, 2010, at 02:46 PM EST