NA49 Beam Line 1996 p Run

Targets, counters, and other material in the H2 beam line

H. Stroebele

17 Oct 1996
C2 Collimator 2 -412000 mm
C3 Collimator 3 -412000 mm
C6 Collimator 6 -341000 mm
T1 Trigger 1 -160000 mm
C9 Collimator 9 -147000 mm
T2 Trigger 2 -100000 mm
T3 Trigger 3 -62000 mm
RC CEDAR -58000 mm
T4 Trigger 4 -54000 mm
S0 Beam Counter -39710 mm
S1 Beam Counter -39460 mm
W1 Window -38880 mm
BPD1 Beam Position Detector -38782 mm
W2 Window -38740 mm
MBPL Bending Magnet for beam cal.-36907 mm
W3 Window -16520 mm
BPD2 Beam Position Detector -16430 mm
W4 Window -16390 mm
S2 Beam Counter.(in vac) not used for Pb -15780 mm
V0 Veto Scint. with hole (in vac) -15530 mm
FISC thin scint. wires -14746 mm
W5 Mylar window -7530 mm
Target0 0.5 mm Ta for multi-target runs -7523 mm
BPD3 Beam Position Detector (not used) -6576 mm
LHT Liquid Hydrogen Target -5800 mm
W6 He-bag Mylar window -5300 mm
VM1 Vertex 1 Magnet and VTPC1 -3802 mm
S4 Beam Counter -1943 mm
Target2 0.5 mm Ta for multi-target runs -1884 mm
VM2 Vertex 2 Magnet and VTPC2 0 mm
Target3 0.5 mm Ta for multi-target runs 1571 mm
W7 SAC He-bag; Mylar window 1575 mm
W8 SAC He-bag; Mylar window 3325 mm
W9 MTPC He-bag; Mylar window 3325 mm
W10 MTPC He-bag; Mylar window 8525 mm
S5 Veto counter 9400 mm
Ring Ring Calorimeter front face 13800 mm
Coll Collimator front face 19200 mm
Veto Veto Calorimeter front face 21800 mm

Send corrections or additions to Art Poskanzer


C2: Collimator 2 -412000 mm

Collimator for the horizontal divergence. Standard setting is about +/-1.5 mm

Adjust the beam intensity by moving the collimators. Collimators 2, 3, and 6 should be approximately the same. If you are closing the collimator, it first opens all the way, so first put the plug (TAX) in to -100 mm. To do so on the EANORTH terminal type RUN TREE, go to TUNE, SPECIAL, TAX, 1, and set to -100. If you are opening the collimator this is not necessary. To move the collimator itself chose TUNE, SET, COLLIMATORS, 2, and type in desired value.


C3: Collimator 3 -412000 mm

Selects central momentum bite. Standard setting is about +/-1.5 mm

Adjust the beam intensity by moving the collimators. Collimators 2, 3, and 6 should be approximately the same. If you are closing the collimator, it first opens all the way, so first put the plug (TAX) in to -100 mm. To do so on the EANORTH terminal type RUN TREE, go to TUNE, SPECIAL, TAX, 1, and set to -100. If you are opening the collimator this is not necessary. To move the collimator itself chose TUNE, SET, COLLIMATORS, 3, and type in desired value.


C6: Collimator 6 -341000 mm

Vertical collimator for vertical size. Standard setting is about +/-1.5 mm

Adjust the beam intensity by moving the collimators. Collimators 2, 3, and 6 should be approximately the same. If you are closing the collimator, it first opens all the way, so first put the plug (TAX) in to -100 mm. To do so on the EANORTH terminal type RUN TREE, go to TUNE, SPECIAL, TAX, 1, and set to -100. If you are opening the collimator this is not necessary. To move the collimator itself chose TUNE, SET, COLLIMATORS, 6, and type in desired value.


T1: Trigger 1 -160000 mm

Scintillation counter for TOF ID of low energy hadron beam.

Should normally be removed. It has 50 cm air and two Mylar windows, each 0.1 mm thick.


C9: Collimator 9 -147000 mm

Cleaning collimator. Be sure not to scrape the beam. Standard setting is about +/-5 mm

On the EANORTH terminal type RUN TREE. To move the collimator chose TUNE, SET, COLLIMATORS, 9, and type in desired value.


T2: TRIG2 appr. -100000 mm

Scintillation counter for beam steering. Has 6 mm Pb for electron conversion.

Should normally be removed. Has 50 cm Air and 2 Mylar windows of 0.1 mm each.


T3: TRIG3 appr. -62000 mm

Scintillation counter for CEDAR adjustment.

Should normally be removed. Has 50 cm Air and 2 Mylar windows of 0.1 mm each.


CEDAR : CEDAR appr. -58000 mm

Ring Cerenkov counter to identify 158 GeV/c protons.

Is made up of 600 cm He and 2 0.4 mm thick aluminum windows. For more information see NA24 beam line folder.


T4: TRIG4 appr. -54000 mm

Scintillation counter for CEDAR adjustment.

Should normally be removed. Has 50 cm Air and 2 Mylar windows of 0.1 mm each.

S0: Beam Counter in vacuum -39710 mm

Was called S1 in 1995 Pb run.

50 mm x 40 mm x 5 mm Scintillator for proton beam. PM tube = XP2020; Max HV=3000.

This counter is mounted on a vertical stage, which can be controlled from inside the counting house in Rack 17.

For the above settings check the log book!

The HV has to bet set to zero before the vacuum in the beam pipe is either broken or reestablished!

Responsible for this Detector: Marburg group


S1: Beam Counter in vacuum for Trigger and TOF -39460 mm

Was called T0 in 1995 Pb run.

50 mm x 30 mm x 5 mm Scintillator for proton beam. PM tube XP2020, Max HV=3000.

This counter is used as the positive beam defining counter for ions and, in addition, as time=0 for TOF.

This counter is mounted on a vertical stage, which can be controlled from inside the counting house in Rack 17.

For the above settings check the log book!

The HV has to bet set to zero before the vacuum in the beam pipe is either broken or reestablished!

Responsible for this Detector: Marburg group


Window 1: Mylar window -38880 mm

vacuum 0.05 mm black Mylar


BPD1: Beam Position Detector -38782 mm

2 planes of MWPC with strip readout.

This detector measures the beam position in x- and y- directions perpendicular to the beam. Each strip is 16 mm wide and they have a 2 mm pitch.

The nominal x- and y-coordinates of its center are

Material in the beam: 0.125 mm Mylar and 24 mm Ar(CH4) gas.

Responsible for this detector: H.G. Fischer CERN and P. Freund, MPI Muenchen


Window 2: Mylar window -38740 mm

vacuum 0.05 mm black Mylar


MBPL: Bending Magnet (in vac) -36907 mm

This bending magnet (2 m long) can be used to deflect the beam for TPC alignment measurements. It is controlled by the beam control console (TREE: magnet name is Bend8).

Its maximum bending power for a 400 GeV/c particle (corresponding to 160 GeV/c Pb beam) is appr. 10 cm at VTPC1. Either spectator protons or secondary hadrons have to be used.


Window 3: Mylar window -16520 mm

vacuum 0.05 mm black Mylar


BPD2: Beam Position Detector -16430 mm

2 planes of MWPC with strip readout.

This detector measures the beam position in x- and y- directions perpendicular to the beam. Each strip is 16 mm wide and they have a 2 mm pitch.

The nominal x- and y-coordinates of its center are

Material in the beam: 0.125 mm Mylar and 24 mm Ar(CH4) gas.

Responsible for this detector: H.G. Fischer CERN and P. Freund, MPI Muenchen


Window 4: Mylar window -16390 mm

vacuum 0.05 mm black Mylar


S2:Beam Scintillator (in vac) -15780 mm

20 mm x 20 mm x 2 mm. This counter is not used for normal Pb running; however, it can be used to tune the beam. PM tube XP2020, Max HV=3000.

This counter is mounted on a vertical stage, which can be controlled from inside the counting house in Rack 17.

For the above settings check the log book!

The HV has to bet set to zero before the vacuum in the beam pipe is either broken or reestablished!

Responsible for this Detector: D. Vranic, CERN


V0: Veto Scintillator (in vac) -15530 mm

80 mm diameter with 10 mm hole. This counter is essential for the clean-up of the beam; it vetoes charged particles and fragments which are produced upstream. PM tube XP2020, Max HV=3000.

This counter is mounted on a vertical stage, which can be controlled from inside the counting house in Rack 17.

For the above settings check the log book!

The HV has to bet set to zero before the vacuum in the beam pipe is either broken or reestablished!

Responsible for this Detector: D. Vranic, CERN


FISC: thin scintillating wires. -14746 mm

Scintillating wires horizontal (FISC 11) for vertical profile and wires vertical (FISC 12) for horizontal profile. This detector belongs to the external beams group (G.P. Ferry) and is controled by the TREE program. It consists of two perpendicular thin wires which are read out by two PM tubes each. The wires are movable under beam console control.

The detector is used to scan the profile of the beam in the plane perpendicular to the beam. Also, the wires can be positioned in the center and scanned with TRIM5 and TRIM6 to fine tune the beam position.

Normally the FISC is aligned such that the reading 0.0 gives the center of the nominal beam. At present (Sep 96) the beam is at - 4 mm on the internal FISC scale.

Responsible for this detector is the external beam group.


W5: Mylar window -7530 mm

vacuum 0.05 mm black Mylar


Target0: Ta for multi-target runs -7523 mm

At the begining of the p run it was at -8615. Present (23 Sep 96) position is best defined by distance to T1: 1723 +/- 1 mm.

Responsible for this item: H. Stroebele Univ. Frankfurt and S. Wenig, CERN


BPD3: Beam Position Detector -6576 mm

2 planes of MWPC with strip readout. This detector cannot be in the beam if the LH Target is in.

This detector measures the beam position in x- and y- direction perpendicular to the beam. Each strip is 16 mm wide and they have a 2 mm pitch.

Material in the beam: 0.125 mm Mylar and 24 mm Ar(CH4) gas.

The nominal y-coordinates of its center is Y_center = 0 mm. It is mounted on a stage movable horizontally remotely controlled from the counting house. To operate the stage go to the Laser Macintosh and choose on the front panel item SMK control The corresponding window allows one to move the stage. Coordinates are in the standard NA49 system.

The stage can also be moved locally by activating one of the end switches; the stage will then move away from that switch. If you move it locally with the remote/local switch of the driver board (see rack 21, lowest crate) on local, you lose position control. In case it happens, it can be recalibrated by moving the detector into the canonical beam position (655.0 mm on the scale fixed to the upper rail) and resetting the counter of the stage control to 0.

Responsible for this detector: H.G. Fischer CERN and P . Freund, MPI Muenchen


LHT Liquid Hydrogen Target -5800 mm

140 mm long 30 mm diameter. For multi-target runs replaced by 0.8 mm Pb target at nominal position of -5800 +/- 3 mm.

Separated from the vacuum by 0.075 mylar windows on both sides; in a target vacuum vessel extending from z=-7420 to z=-57902. The upstream window of the vessel has a diameter of 30 mm (0.05 mm Mylar) and the downstream window a diameter of 180 mm (0.125 mm Mylar).


W6: He-bag -5300 mm

0.02 mm Mylar.


VM1: Vertex 1 Magnet and VTPC1, nominal position -3802 mm

For VTPC1 see elsewhere.

For magnet operation see the magnet control screen.

In case of trouble with current control call In case of trouble with cryogenics call


S4: Beam Counter -1943 mm

Scintillator 10 mm thick by 20 mm diameter. Hamamatsu tube, Max HV=2300 V.

For horizontal movement see BPD3.


VM2: Vertex 2 Magnet and VTPC2, nominal position 0 mm

For VTPC2 see elsewhere.

For description of VM2 see VM1.


Target3: Ta for multi-target runs 1571 mm

0.5 mm Ta. The target is mounted on a pivoting arm which can be moved up and down remotely from the counting house. The corresponding buttons and indicators are mounted in the very top row of rack 15. Always make a visual inspection of what happened.

The nitrogen supply labeled "LASER" in the gas cave has to be open for operation. Also, the pressure reducing valve on top has to be open. One of the two indicators will be lit, if there is pressure in the corresponding line to the cylinder. There are additional valves after the sensors in these lines which have to be open! They are mounted on the front face of VTX1 at the very lower left side. The indicators light up, if the corresponding limit positions are reached. Thus the target may be in the beam if the "target out" light is not lit.


W7: SAC He-bag 1575 mm

15 micron Al + 85 micron Mylar. The beam passes through the normal He bag walls. The material is foil A30 from NAWROT GmbH, D-51688 Wipperfeld, Fax 02268 2701.


W8: SAC He-bag 3325 mm

15 micron Al + 85 micron Mylar. The beam passes through the normal He bag walls. The material is foil A30 from NAWROT GmbH, D-51688 Wipperfeld, Fax 02268 2701.


W9: MTPC He-bag 3325 mm

100 micron Mylar


W10: MTPC He-bag 8525 mm

100 micron Mylar


S5: Veto counter 9400 mm

30 mm diameter x 10 mm thick. Phototube XP 2262B, Max HV 2500 V.

It is used for multi-target runs only This counter is mounted on a stage movable in the plane perpendicular to the beam, which is remotely controlled from the counting house (rack zz).

The current (Sep 96) nominal positions in the beam for field-off

and standard magnetic field The HV setting is 2000 V. Always verify in the log book!


Ring: Calorimeter front face 13800 mm


Coll: Collimator front face 19200 mm

The vertical opening is +/-50 mm. In the STD+ configuration the horizontal opening goes from -50 mm to +380 mm.


Veto: Calorimeter front face 21800 mm


Please send corrections to Herbert Stroebele

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