SPS North Area Operation
Shutdown Lectures - 2006
Morning session
 Introduction and test beams
Ilias Efthymiopoulos
Afternoon session
 M2 muon beam – COMPASS
 Neutrino beam – CNGS
Lau Gatignon
Edda Gschwendtner
And…


PS East Area operation
nTOF/FTN line operation
M. Delrieux (17 March – PM)
not operational in 2006
The SPS North Area Beams
Outline






Introduction (6)
The EHN1 Beams (18)
Design highlights (12)
Operational aspects (4)
Safety Issues (8)
Access System
Ilias Efthymiopoulos AB/ATB-EA
SPS Training Lecture Program
March 2006
Introduction (1/6)

The proton beam (400 GeV/c) from SPS is slowly extracted to the North Area at LSS2

The extracted beam is transported in the TT20 tunnel


11% slope to arrive into TCC2 – then horizontal ; ~10m underground
The primary proton beam is split in three parts directed towards to the North Area
primary targets: T2, T4 and T6
11% slope
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Shutdown Lectures 2006 - 3
Introduction (2/6)
The splitters – how they work!
Field-free region

B
Horizontally deflected by the
B-field
Continues straight - no B-field
Losses

Optimized beam optics to minimize losses


Small bH (~9m) and large bv(~23Km)
The beam splitters are among the “hottest” objects in TCC2
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T2
T4
T6
Shutdown Lectures 2006 - 4
Introduction (3/6)
The SPS North Area Beams
 The three proton beams are directed onto the primary targets:

T2  H2 and H4 beam lines

T4  H6, H8, and P0 beam lines

T6  M2 beam line
and Experimental Areas:
 ECN3: underground experimental hall, can receive the primary proton beam
with high intensity in ECN3

EHN1: surface experimental hall, can receive secondary beams and/or
attenuated primary proton beams

EHN2: surface experimental hall, receives the secondary beams or intense
muon beam
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Shutdown Lectures 2006 - 5
Introduction (4/6)
EHN2
EHN1
(COMPASS)
ECN3
BA80
(NA48)
(ps building)
TCC2
access
CRN
(obsolete)
TCC2
targets
BA81
(underground)
(ps building)
CCC
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Shutdown Lectures 2006 - 6
Introduction (5/6)

6.5 Km of
beam lines

About 1000
equipment
installed
NA49
CALICE/ILC
GLAST, DREAM, AMS,…
CMS
ALICE
CERF/SC-RP
CRYSTALS/LHC Coll.
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LHCb
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ATLAS
TOTEM
Shutdown Lectures 2006 - 7
Introduction (6/6)
SPS Secondary Beam Lines - Experiments/Tests
Total
35
30
LHC-Experiments
Tests
FT-Experiments
25
20
15
SPS Secondary Beam Lines - Sub-periods (user slots)
10
5
Indium Run (40 days)
(14 additional sub-periods)
100
90
0
2001
2002
2003
2004
Year
2005
80
2006
70
60
50
Extrapolation for 2006
(all requests - shorter time slices or new areas)
Extrapolation for 2006
(keep weekly tests)
40

2006 will be a very interesting
year for operations…
30
20
Total
10
West Area
0
2001
2002
2003
2004
2005
2006
Year
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Shutdown Lectures 2006 - 8
The EHN1 beams (1/18)

The SPS North Area was originally designed to house long-lasting experiments


In the recent years most of the users are “tests”



demands for high quality of beams: high intensity, high energy, high resolution
in particular of LHC detectors with permanent or “semi-permanent” BIG installations
several users from astroparticle experiments
The test users have very different requirements from the big experiments:

scan the full energy range ; typically [10, 300] GeV/c


use beams of all particle types {electrons, pions, protons, muons}


with sometimes increased precision (linearity) requirements
with as good as possible separation and identification
and, sometimes request high (or very high) rates
and all that during the few (or even one!) week(s) of their allocated time!
Rapidly changing environment, quite demanding on beam conditions and tunes
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Shutdown Lectures 2006 - 9
The EHN1 beams (2/18)
Target Beam Characteristics
T2
T4
H2
High-energy, high-resolution secondary beam.
Alternatively can be used to transport: attenuated primary beam of
protons, electrons from g-conversion, polarized protons for L0 decay,
enriched low-intensity beam of anti-protons, or K+
Main parameters: Pmax= 400 (450) GeV/c, Acc.=1.5 mSr, Dp/pmax= ±2.0 %
H4
High-energy, high-resolution secondary beam.
Alternatively can be used to transport: primary protons, electrons from gconversion, polarized protons for L0 decay, enriched low-intensity beam of
anti-protons, or K+
Main parameters: Pmax= 330 (450) GeV/c, Acc.=1.5 mSr, Dp/pmax= ±1.4 %
H6
High-energy secondary beam.
Main parameters: Pmax= 203 GeV/c, Acc.= 2.0 mSr, Dp/pmax= ±1.5 %
H8
High-energy, high-resolution secondary beam.
Alternatively can be used to transport an attenuated primary proton beam
Main parameters: Pmax= 400(450) GeV/c, Acc.= 2.5 mSr, Dp/pmax= ±1.5 %
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Shutdown Lectures 2006 - 10
The EHN1 beams (3/18)
Particle production downstream the primary target
Primary p beam
(400 GeV/c)
Secondary particles ( 400 GeV/c)
Target
Development of hadronic shower

Protons : remnant of the incoming primary beams



Typical scale: interaction length (lint)
Electrons : produced in electromagnetic processes


the target actually serves as attenuator
~40% of the initial incoming intensity of the beam
Pions(hadrons) : produced in hadronic interactions


Attenuated proton beam
Typical length scale : radiation length (X0)
Muons : produced in the decay of pions

21/03/2003
At the target and also along the beam line
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Shutdown Lectures 2006 - 11
The EHN1 beams (4/18)
Target material and length
 The proton intensity on each target can go up to 1013 protons/pulse

limited by target and TAX absorber construction (i.e. cooling, etc.)

The material with largest ratio: Xo/lint is preferred  Beryllium

Increasing the target length:

more production but also more re-absorption

lower the energy of the outgoing particles
Optimal choice ~ 1 interaction length
Material
Beryllium
Copper
Lead
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Xo
lint
(cm)
(cm)
35.3
1.50
0.56
40.7
15.0
17.1
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Xo/lint
0.87
0.10
0.03
Shutdown Lectures 2006 - 12
The EHN1 beams (5/18)
The target head
Beam position monitors
T2 target
Position H (mm) V (mm) L (mm) Material
0
EMPTY
160
2
300
Be
1
160
2
500
Be
2
160
2
180
Be
3
160
2
100
Be
4
120
2
40
Be
5
T4 target
Position H (mm) V (mm) L (mm) Material
0
EMPTY
160
2
300
Be
1
3
2
300
Be
2
160
2
200
Be
3
160
10
100
Be
4
120
40
Pb
5
21/03/2003

TBIU (upstream) , TBID (downstream)
<x> = -0.2 mm
<y> = -0.4 mm


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mounted on same girder as the target
head for better alignment
beam steering onto the target using
BSM located ~30m upstream of the
target
Shutdown Lectures 2006 - 13
The EHN1 beams (6/18)
T6 target
(M2, COMPASS)
T4 target
(H6, H8, P0)
T2 target
(H2, H4)
Wobbling magnets
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Shutdown Lectures 2006 - 14
The EHN1 beams (7/18)
Special cases – tertiary beams from neutrals
 Neutral particles (g, K0, L0) are also produced at the target

Use a strong magnet to sweep
away all charged particles

Let the neutrals fly through
towards the beam line direction

Use the first magnet of the
beam to select the sign of
particles to transport
And …
1. Convert the photons using a lead sheet to produce e+, e- pairs
 That way we can produce the purest electron/positron beams !!!
2.
Let short lived neutrals (K0, L0) to decay in air to produce p or p beams
 Using the energy and decay kinematics can enhance the p, p content of the beam
21/03/2003
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Shutdown Lectures 2006 - 15
The EHN1 beams (8/18)
Special cases – Muon beam characteristics
 Muon beams are formed by the decay of pions (p+, or p-)
Decay kinematics:
 At the pion center of mass system:
2
2
m
m
p
m
p* 
 30 MeV c
2 mp
2
2
m
+
m
m
E*  p
 110 MeV c
2 mp

At the laboratory frame – boost

Limiting cases:
q*
m
n
Em  g p E* + bp p* cos * 
Conclusion:
 the muon beam energy is in the
interval [0.57,1.0] of the initial pion
beam energy
cos  +1  Emax  1.0  Ep
cos  -1  Emin  0.57  Ep
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m (p*, E*)
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0.57 
Em
Ep
 1.0
Shutdown Lectures 2006 - 16
The EHN1 beams (9/18) – Production rates
Electron beams
Particle production by 400 GeV/c protons on Be targets,
H.W.Atherton et. al.
Hadron beams
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Shutdown Lectures 2006 - 17
The EHN1 beams (10/18) – target station wobbling
AIM
 Additional degrees of freedom  increase the flexibility in using a target station

Produce “several” secondary beams from the same target
 when the primary beam hits the target basically “all” the particles are produced in a
large variety of angles and energies
 the most energetic particles are in the forward direction
should not forget:
 The very intense primary proton beam has to be dumped in a controlled way

The secondary beams of the chosen momentum have to go into the directions
foreseen by the beam geometry (i.e. inside the vacuum tube of each beam
line)
Solution:
 “wobbling” : hit the target under variable angle
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Shutdown Lectures 2006 - 18
The EHN1 beams (11/18) – target station wobbling
0-order approximation:
SPS protons
B1
Target
1st -order approximation:
SPS protons
TAX
• single secondary or
primary beam
• fixed production angle
TAX
B1
• two secondary beams
• one could be the
primary beam
Target
• fixed production angles
2nd -order approximation:
TAX
B1
B1
Target
• two secondary beams
• one could be the
primary beam
• variable production
angles
SPS protons
B1
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Shutdown Lectures 2006 - 19
The EHN1 beams (12/18) – T4 target station
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Shutdown Lectures 2006 - 20
The EHN1 beams (13/18) – TAX absorber attenuator
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Shutdown Lectures 2006 - 21
The EHN1 beams (14/18) –– TAX absorber attenuator
Preparation and installation of new TAX blocks for T4.
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Shutdown Lectures 2006 - 22
The EHN1 beams (15/18) – T4 Wobbling
Example 1:
 primary proton beam in P0
 H8, H6 secondary beams
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Shutdown Lectures 2006 - 23
The EHN1 beams (16/18) – T4 Wobbling
Example 1:
 primary proton beam in P0
 H8, H6 secondary beams
Presently the most frequent case
“standard wobbling” settings:
H8
Energy (GeV/c)
@ 0 mrad prod. angle
+180
+20
-250
21/03/2003
H6
Energy
(GeV/c)
+120
+100
+80
+10
+20
+6
-100
-200
-120
-60
Prod. Angle
(mrad)
0
-5.46
-13.36
-1.58
8.58
-15.13
-0.33
8.06
2.15
-10.23
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Shutdown Lectures 2006 - 24
The EHN1 beams (17/18) – T4 Wobbling
Example 2:
 P0 beam OFF
 primary protons in H8 – “micro-beam”
 H6 secondary beam
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Shutdown Lectures 2006 - 25
The EHN1 beams (18/18) – T4 Wobbling
Safety - Survey
 survey (monitor) the current in the “wobbling” magnets and the position
of the TBIU, TBID monitors should be automatically done

A program called WOBSU should be running continuously
 for planned changes to the target station magnets (wobbling changes)
a manual INHIBIT signal for the extraction has to be set at the CCC
Wobbling changes:
 initiated by the EA physicist upon the user requests
 presented and discussed in the EATC meeting, documented in the
minutes
 settings file prepared and communicated by the EA physicist
 performed by the operators on the agreed time

21/03/2003
re-tuning of the the beam lines after the wobbling changes is often
required
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Shutdown Lectures 2006 - 26
Design highlights (1/12)

The momentum selection is done in the vertical plane
“downstream” V-BENDs (B3, B4)
the main spectrometer of the
beam momentum definition
“upstream” V-BENDs (B1, B2)
21/03/2003
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between the primary target and
the momentum acceptance
collimator
Shutdown Lectures 2006 - 27
Design highlights (2/12)
View of the H8 and H6 beam lines in TT81 tunnel.
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Shutdown Lectures 2006 - 28
Design highlights (3/12)
Beam optics modes:
 High Resolution: used in the past to increase the momentum
resolution of the beam line
 Required additional hardware (spectrometer chambers), not available
anymore.
 High Transmission: allows having the maximum particle flux at a
given momentum
 Filter Mode : has a focus on both planes at ~130m of the beam line,
which allows using an intermediate (tertiary) target
 Heavily used now days to produce tertiary beams !
 Tertiary beams provide more flexibility to the users and relaxes the
coupling between the beam lines due to wobble choice.
 keep longer periods with the same wobble setting
21/03/2003
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Shutdown Lectures 2006 - 29
Design highlights (4/12)
Tertiary beams
 Produced in two distinct ways:

H6, H8: use a second target (filter)
 beam line tuned for two energies:



E1 (high energy) : from the primary target until the filter

momentum selection by the “down” vertical BENDs
E2 (< E1) : from the filter until the experiment

momentum selection by BEND-3 and BEND-4 (up vertical bends)
H2, H4: from the conversion or decay of secondary neutral particles
 tertiary muon beams of well defined momenta are produced by
stopping pions in a closed collimator before the last bending magnets
of the beam line
21/03/2003
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Shutdown Lectures 2006 - 30
Operational aspects
Design highlights (5/12)
21/03/2003
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Shutdown Lectures 2006 - 31
Operational aspects
Design highlights (6/12)
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Shutdown Lectures 2006 - 32
Design highlights (7/12)



introduce a target (filter) after the
“upstream” bends
tertiary beams have typically lower
rates
choice of target material can
enhance/select different particles

Cu, Poly, Pb
XCON fine positioning filter/converter
21/03/2003
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Shutdown Lectures 2006 - 33
Design highlights (8/12)
Tertiary beams H2 , H4
 use the B3 magnet of the wobbling
as sweeping magnet

use the converter


charged particles are absorbed in
the TAX
 neutral particles go through and hit
the converter
note:
 neutral particles can have zero or
non zero production angle
21/03/2003


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g on Pb (CONVERTER=LEAD): to
produce electrons (e+, e-)
COPNVERTER=AIR (no
converter) to let K0, L0 , to decay
 K0  p+ + p L0  p + p-
use B1 of the beam line to select
the charge and particle for the
tertiary beam to the experiment
Shutdown Lectures 2006 - 34
Design highlights (9/12)
Electron beams
Secondary beams
 electrons produced at the primary
target





longer targets help electron
production


rate goes down with energy
increase
Tertiary beams
 H6, H8: use Pb as secondary
target
rate ~proportional to target length
at high energies (120 GeV/c) can
be separated from hadrons by
synchrotron radiation


21/03/2003
H2, H4: electrons from photon
conversion

mixed beams pion (hadron)
contamination for lower energies
few mm, or ~1-2 radiation lengths
(X0)
radiation length: distance in matter
where
 electrons loose ~1/e of their
energy
 hadrons loose ~nothing
high purity beams!
user CEDAR or treshold
Cherenkov counters for tagging
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Shutdown Lectures 2006 - 35
Design highlights (10/12)
 Electron beam separation by synchrotron radiation at high energies
41mrad angle – DE@180 GeV/c = 200
MeV
Hadron beam – no energy loss
Electron beam – E0-DE
@150 GeV/c  149.197 GeV/c
Electron beam- E0
Electron beam- E0
21/03/2003
41mrad angle – DE@180 GeV/c = 200
MeV
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Shutdown Lectures 2006 - 36
Design highlights (11/12)
Hadron beams
Secondary beams
 hadrons are produced at the
primary target
 for positive sign beam a good
fraction of the total hadron rate is
protons
 using an absorber (~1-2 X0 of Pb)
in the beam we can eliminate any
electron contamination
Tertiary beams
 H6, H8: use secondary target of
Cu, (CH)n



H2, H4: hadrons produced in the
decay of neutral mesons

21/03/2003
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~1 interaction length lI
interaction length: characterizes
the average longitudinal
distribution of hadronic showers
 a high energy hadron has 11/e probability to interact
within one lI
 lI >> X0 for most of materials
L0  p + p-, K0  p++ p-
Shutdown Lectures 2006 - 37
Design highlights (12/12)
Muon beams
Secondary beams
 muons produced directly at the
target area or by the decay of pions

muon momentum: 57-100% of the
parent pion momentum

to produce a pure muon beam for
the experiment, is enough to close
out of beam axis the last
collimators of the beam line

closing the collimator upstream of
the last bend of the line we can
obtain momentum selected muons
21/03/2003

rule of thump: muons in a
1010cm2 trigger represent ~1% of
the hadron/pion flux


there is another ~1% in a cone
about 1  1m2 around the beam
axis
106 muons / 10  10 cm2 trigger
 1.3 uSv/h
Tertiary beams
 muons present only for tertiary
beams in the energy range 57100% of the secondary beam
momentum
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Shutdown Lectures 2006 - 38
Operational aspects (1/4)
Beam tuning
 Goal: deliver good quality of beam to the experiment!

sufficient rate, spot size, particle purity,…
 Tuning the beam is required each time we change something:

energy, wobbling, user
Very important:
 start from an already prepared beam file by the EA physicists
 be sure it corresponds to the present wobbling settings
 be sure it can fulfil the user requirements

21/03/2003
typically the users know “their” files, but good to check it yourself as well!!!
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Shutdown Lectures 2006 - 39
Operational aspects (2/4)
The first steps
 consult the logbook of the beam line


most of the files have been used already in the past
new files represent minor variations of existing files
 treat each plane independently

start with the vertical plane which is the most important to get the beam to
the experimental hall
 select your observation point

a scintillator counter close to the end of the beam line
 provided the beam can reache it!!
21/03/2003
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Shutdown Lectures 2006 - 40
Operational aspects (3/4)
Watch out !!
 electrons do not like material!


remove triggers or other detectors
from the beam line, otherwise you
may simply kill the whole beam
follow the particles, consistent particle
rates



be careful when you try to
measure/monitor things, since you
may disturb the users
use as much as possible normalized
rates: rate/pot
monitor beam losses, be sure you are
looking at the beam not at its halo
 similar rates at different places
along the beam line
Operational aspects


referring to logbook is fine but

21/03/2003
be sure you are comparing apples
with apples

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scintillator counters are typically  =
100mm but NOT ALL; Exp. Scalers can
vary a lot!
switching beam files:

secondary beams have high rates 
acceptance collimators close

tertiary beams have low rates 
acceptance collimators wide open
therefore:
switching from tertiary to secondary beam,
load FIRST the collimators and then the
magnets
Shutdown Lectures 2006 - 41
Operational aspects (4/4)
Important
 Think before acting

Operational aspects
Some users are quite experienced
with their beam, and can do many
things alone

Good documentation is vital
To first order, all beam lines are
quite similar



however there are some
differences which need time to
become familiar with

Time is important for you and the
users

there is always a limit to how good
a beam can be; let the users
decide

21/03/2003
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beam line snapshot:
 status of
magnets/files/wobbling
settings
 status of collimators, target,
absorber
 rates in few counters (start,
middle, end of beam line)
Don’t be afraid to ask for help
Shutdown Lectures 2006 - 42
Safety Issues (1/8)
Radiation Safety Issues
Direct in-beam exposure should be avoided at all cases!

Hadron or electron beams containing >108 particles/burst are dangerous

should be always dumped in special (thick) dumps (controlled losses)





serious irradiation to persons standing close to unshielded loss points
unshielded loss points will cause excessively high radiation levels in the
experimental hall and cause dose rate limits at the CERN boundaries
any in-beam exposure for even one pulse will cause observable biological damage
beam line & areas should be completely shielded
Hadron or electron beams containing >106 particles/burst should be treated
with respect



21/03/2003
unshielded loss points will cause limiting radiation levels in the experimental halls
and at the CERN boundaries
all loss points must be completely shielded (dumps)
any in-beam exposure is still serious and will cause significant administrative actions
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Shutdown Lectures 2006 - 43
Safety Issues (2/8)
Radiation Safety Issues
 Hadron or electron beams containing <104 particles/burst


could be allowed to travel in open areas
still in-beam exposure should be avoided
 Heavy ion beams of any intensity


21/03/2003
cannot be allowed to travel through open areas
accidental in-beam exposure is dangerous and must be completely
avoided
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Shutdown Lectures 2006 - 44
Safety Issues (3/8)
SC/RP Central DAQ
 All installed radiation alarm
monitors can be read remotely
 Data are stored in a database
for further retreival
 The parameters for each
monitor are accessible

21/03/2003
can only be set/modified by
authorized persons (TIS/RP)
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Shutdown Lectures 2006 - 45
Safety Issues (4/8)
21/03/2003
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Shutdown Lectures 2006 - 46
Safety Issues (5/8)
Additional radiation sources in the areas
Radioactive sources
 Used by the experiments for their detector calibration
 Transport/installation under the TIS/RP responsibility
 Normally a garage position should be available

sometimes the source is in interlock with the area access system
 Warning panels at the door of the experimental area
Lasers
 Used by the experiments for their detector calibration
 Normally setup certified by TIS/RP
Radioactive detectors
 Uranium calorimeters (not anymore “a la mode”!)
 “hot” detectors after irradiation tests

transport/installation under TIS/RP supervision
Note
 Setups are modified quite often by the users

21/03/2003
it can happen that information on the changes arrives very late
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Shutdown Lectures 2006 - 47
Safety Issues (6/8)
Dumps
 Used to orderly stop the
hadron/electron beams


For high intensity beams the dump is
made re-entrant, the particles are
dumped into a hole, in order to reduce
the particle backsplash

For very high intensities or for special
beams (neutrino or muon beams) the
dumps consist of many meters of iron,
concrete and/or earth shielding
muons go through but undergo
multiple scattering ==> larger cone
Typically formed by




2-3 m of iron with at least 80cm in
each direction from the beam
impact point
one or two concrete blocks (80cm
each) in each direction
Several dumps can exist in a beam
line


21/03/2003
provide separation between
different experimental areas
 motorized or build in
fixed dump at the end of each line
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
examples: M2, P0/NA48, WANF, CNGS
Shutdown Lectures 2006 - 48
Safety Issues (7/8)
Motorized dumps
XTDX – horizontal
 2-3m of cast iron
 several blocks one next to the other


XTDV – vertical
 3.2m of cast iron
 Is embedded in concrete shielding
variable configuration
 replace by concrete the last block
for better neutron absorbtion

> 80cm in each direction
No concrete shielding around it

21/03/2003
reinforced shielding in the area
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Shutdown Lectures 2006 - 49
Safety Issues (8/8)
Fences
 Used to mark the limits of the controlled areas




at least 2m height
should not be possible to climb over
no ladders allowed at any point against the fences
At least 1-2 m away from the nominal beam axis

exact size/shape depends on the size of the experiment
Modification to dumps or fences
 Can ONLY be initiated by the responsible physicist
 Have to be approved by TIS/RP and RSO


presented in AB Safety Committee for approval
During SPS operation if for whatever reason the dumps or fences of the areas
have to be modified, the MANUAL VETO of the beam line should be set
21/03/2003
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Shutdown Lectures 2006 - 50
The access system (1/8)
Beamline and Experimental Area
classification
 Secondary beam areas





Primary beam areas



21/03/2003
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EHN1 (H2, H4, H6, H8)
EHN2 (P61/M2)
access granted locally
interlock system per beam
line/area
TCC2 (north area targets)
ECN3 (P0)
same access rules as SPS
machine and target zones
Shutdown Lectures 2006 - 51
The access system (2/8)


The access system is used to prevent in-beam exposure for the personnel
For EA can be separated in two categories: Beam lines and Experimental areas
Experimental Area
 Perimeter defined by concrete blocks and/or fences




Doors to access each area


the main one (PPE) and at least one emergency escape door (PPX, PPG)
Several can exist in a single beam line


typically at least 1m from the beam axis, exact shape depends on detector/installation size
high intensity (>106/ppp) proton or heavy-ion beams and exp. areas are completely shielded with
concrete
visibility to the area should not be blocked
connected to the same or different interlock chains
Access to downstream areas depend on beam conditions

provided there is a dump (XTDV, XTDX, “manual”) in between
Beam Line
 The beam line: from the target  tunnel  exp.area(hall)  dump
 A beam line can contain a single or several interlock chains of experimental areas
21/03/2003
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Shutdown Lectures 2006 - 52
The access system (3/8)
PPE146 – H6A
 Big but “empty”
PPX146
XTDV
PAX monitor
PPE146
21/03/2003
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Shutdown Lectures 2006 - 53
The access system (4/8)
PPE168 – H8B



Large area with four doors and a search point
Big and complicated detector installations
Radioactive sources, gas distribution (including flammable)
PPX168
PPG168
Search point
PAX monitor
XTDV dump
Magnet interlock
PPX168
21/03/2003
Beam dump
PPE168
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Shutdown Lectures 2006 - 54
The access system (5/8)
Safety elements
 Physical elements that provide information for the access system

Doors: allow access to the experimental areas and underground tunnels

Dumps: motorized dumps to separate experimental areas in the same beam
line

TAX: motorized blocks “dumps with holes” to attenuate or dump the beam

Magnets: stop the transport of a beam; (“champ null” detector, current limit,
interlock)

Equipment: has to be present and in a given configuration

Special case: radiation monitors


can stop the beam if above threshold, but not included in the access system
Status information available on the control room
21/03/2003
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Shutdown Lectures 2006 - 55
The access system (6/8)
Interlock chains
 Hardware system to define a status of a beam line



Hierarchical organization




receives/treats information form various safety elements
specialized electronics and network
per beam line (several chains in each beam line)
tunnel (several beam lines)
building/tunnels/area (TTC2=North)  SPS veto
Interlock signal based on information from at least two safety elements
21/03/2003
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Shutdown Lectures 2006 - 56
The access system (7/8)
Software Interlock chains - Matrices
 Implemented into NODAL (CESAR) system

Should correspond to the actual hardware configuration


matrices describing the configuration of each interlock chain
Used to facilitate the users/operators


avoid mistakes that can cause access alarms
fast help and monitor of the access system
however
 Mainly intended for high-level commands/programs


direct calls to the hardware (ie. move a TAX or XTDV) may still be possible
Software interlocks are not considered as SAFE
Note:
 Hardware for the interlock system maintained by M.Grill (ST/MA)
 Annual inspection before SPS startup
21/03/2003
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Shutdown Lectures 2006 - 57
The access system (8/8)
Safety Elements
Doors

Control the access to experimental areas and
beam lines

Users have to take a key to open the door


marked at PPE xxx, PPX xxx (PPG xxx)



21/03/2003
free  key access

search of the area by SPS operators and
the GLIMOS of the experiment
key access  beam (beam  key access)

press the end of access system


free: people can enter without key
key access: to enter you have to take a key
beam ON/OFF: no access, beam can be
present in the area
if a door is left open more than 1min switches
automatically to free state
In complicated areas the PPExxx door is
combined with a search point
no more than 8 people at a time in the area
if so, the door/area must go in free mode
Change of door/area states:

Timeout (~1min)



must use the key to enter AND exit the area
Door status defines the status of the area
BUT NOT of the beam line






At least one PPE and one PPX in each area


Access Rules to Experimental Areas

One person one key
verify that the above rule was not violated

via computer system
key access  free

via computer system

door open timeout
Emergency button (“force the door”)

stops the beam

drops the interlock chain of the door

AND the next higher level interlock chain
acts like a door
forces the area patrol to pass by that point
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Shutdown Lectures 2006 - 58
The access system (9/8)
PPExxx Door
keys
door and
area status
and control
panel
door handle
21/03/2003
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Shutdown Lectures 2006 - 59
The access system (10/8)
Dumps – Motorized XTDV, XTDX
 Used to separate experimental areas in the same beam line

attached to the interlock chain of the downstream area
 Motorized XTDV, XTDX dumps, 2-3m of Fe
 Two positions defined: IN/OUT
 Before moving a dump the beam must be stopped

this to avoid spraying particles as the edge of the dump crosses the beam
Magnets
 Power converter level


interlock on polarity
current limitation
 Direct measurement of the magnetic field


21/03/2003
zero magnetic field detection (“champ null”)
can be very tricky if we have to transport low energy beams
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Shutdown Lectures 2006 - 60
The access system (11/8)
TAXs – Target Attenuator
 Massive blocks of material (Al-Cu-Fe)



Combined function:



Access system
dump: stop proton/hadron beam
 can be quite “hot”; ~5 Sv/hr at the end of shutdown
attenuator: let the full (big hole) or attenuated beam (small holes with some material insert) to
go through
Fully motorized with remote control


different configurations depending on the beam line
3.2m long located downstream the primary targets
two motors (XTAXxxxyyy) per beam
Movement split in ranges

SMALL range:
 move around the small holes



21/03/2003
empty or with material insert
 used for the primary proton beams
MEDIUM range:
LARGE range:
 can move the full range including the big empty holes
 used for secondary or ion beams
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Shutdown Lectures 2006 - 61
The access system (12/8)
21/03/2003
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Shutdown Lectures 2006 - 62
The access system (13/8)
Equipment
MicroCollimator in H8 Beam Line
 Combined setup:




set of two collimators: XCRH and
XCRV
their support table: XCRT
an IN/OUT collimator: XCIO
Used for the “micro-beam” option in
H8

21/03/2003
attenuated primary proton beam in
H8
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Shutdown Lectures 2006 - 63
Interlock Chain – North Area
The access system (14/8)
21/03/2003
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Shutdown Lectures 2006 - 64
The access system (15/8)
Interlock chain status
The chains can be:
SAFE
 If all the elements in
the chain are in the
SAFE state

it means we can
have access to
the area
or
UNSAFE
 If any of the
elements in the
chain is in UNSAFE
state


21/03/2003
we can’t have
access
the beam is
present
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Shutdown Lectures 2006 - 65
The access system (16/8)
Door Status and Control
Display
 Displays the status of
the PPE doors
 Allows monitoring
and control of their
state
The doors can be in one
of the following states
FREE (green)

No access control
KEY ACCESS (yellow)


Access with key
Limited number of
people
CLOSED (red)

21/03/2003
Beam present
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Shutdown Lectures 2006 - 66
The access system (17/8)
Search and secure procedure
 Is needed in order to switch from
Free to Key access an Exp. Area

2.
Verify that all fences and blocks defining the perimeter of the area are in place
3.
Remove all ladders or any other equipment can be used by people to climb over the
fences
4.
Go to the PPE door and call the PCR to switch it from “Free Access” to “Key Access”
5.
Leave one person at the PPE door and start the search. All persons entering the
area must take a key. Audible devices can be used during the search to warn
people. Take your time and look carefully everywhere
6.
If there is a “Search Box” you must re-arm it
The search is conducted by


Procedure:
1.
Ask all the persons present in the area to exit and close all the doors (PPE, PPX,
PPG)
the search leader
 normally the GLIMOS of the
experiment and other
authorized persons(s)
The defined procedure should be
rigorously followed
7.
21/03/2003
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

although there is a time-out to do so, don’t rush!
it is more to force you to look into that area not just to turn the key!
Return all the keys to the PPE door and press the “End of Access” button
Shutdown Lectures 2006 - 67
The access system (18/8)
North Area Beam Interlock
Proton extraction to the North is allowed
only if the North Area is in SAFE mode

North Area SAFE when ALL the
corresponding Beam Lines are in safe
mode

Beam Line SAFE if
- either the nominal beam energy is limited
below the energy of primary protons
 ie. cannot transport primary
protons
or the beam intensity is limited by beam
attenuators (TAX's or combination of
TAX's and other beam elements)
Ion beam extraction can always be done
 Particle type identification from CPS


21/03/2003
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“Oxygen Interlock” signal
Manual operation – “ion key”
Shutdown Lectures 2006 - 68
The access system (19/8)
Example H8 Beam Line:
Normal status
Element
Beam Line
TAX
SAFE
UNSAFE
TAXMOT(6)
Magnets
BEND
Micro collimator table TABLE201
Micro collimator
XCRH201
XCRV201
Protection collimator
XCIO200
NO RGE
ALARM
LIMITED
NON LIMITED
SAFE
UNSAFE
SAFE
UNSAFE
SAFE
UNSAFE
SAFE
UNSAFE
Actual
Status
0
1
1
Micro Beam
(primary protons)
1
0
1
0
1
0
1
1
1
1
1
0
1
0
1
1
0
1
0
1
0
1
0
Protons
Ions
(secondary)
1
x
0
x
1
1
1
0
0
1
x
x
x
x
0
1
x in a position means that 1 or 0 is allowed
21/03/2003
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Shutdown Lectures 2006 - 69
0
1
0
1
x
x
x
x
0
1
The access system (20/8)
TAX Ranges
 SMALL/MEDIUM Range


only small holes or holes with
insert  attenuated beam
LARGE Range

21/03/2003
big and/or empty holes possible 
no attenuation
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Shutdown Lectures 2006 - 70
The access system (21/8)
TAX Ranges
 status and setting in NODAL CESAR






READ
TAXDT
an access
SELECT.RGE
ENABLE.RGE
machine/beamline
CONTROL.RGE
ACTUAL.RGE
21/03/2003
actual position (readout)
set position (default, BIM-0). The position to reach at the end of
selected range (set)
allowed (enabled) range based on the beam type in the
control unit status (values: COMPUTER, LOCAL, LOCKED)
actual range (readout)
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Shutdown Lectures 2006 - 71
The access system (22/8)
BEND Limits
Interlock condition on the maximum
allowed current for the main
BENDs of a beam line
 LIMITED: Ilimit < ISPS


North Area
the primary SPS beam cannot be
transported
UNLIMITED: Ilimit  ISPS

21/03/2003
the primary SPS beam can be
transported
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Shutdown Lectures 2006 - 72
The access system (23/8)
Manual Veto

“Key” to veto an interlock chain of a beam line

blocks the presence of the beam in an exp.
area, regardless the status of the existing
safety elements of the chain

Normal status of all exp. area chains during
shutdown

Has to be set each time there is work
foreseen that can modify the status of an exp.
area

Can ONLY be lifted with the agreement
(signature) of the EA physicist.

The EA physicist must patrol the exp. area
before signing to lift the Manual Veto


verify that its perimeter is correctly closed
the safety elements (dumps, doors, magnets)
are present and functional
i.e. must verify that the access system can function
correctly
21/03/2003
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Shutdown Lectures 2006 - 73
The access system (24/8)
Changes to the access system
 Changes to the access system (new conditions from the users,
modification in the beam line or exp. area) are initiated and are
under the responsibility of the EA physicist
 The EA physicist takes care that all the parties involved are consulted
and agree on the proposed changes



EA and BI beam line experts
access system experts, ST/MA (M. Grill)
TIS/RP and AB/RSO
 All modifications are discussed in the EATC meetings and documented
in the minutes


21/03/2003
1st meeting of the year: summary of all modifications during the shutdown
during operation, in the meeting before the SPS period concerned
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Shutdown Lectures 2006 - 74
Items not discussed
 SPS Page-1 – what it means every number there?
 Timing –events and their distribution
 Beam Instrumentation

Collimators, FISCs, WireChambers, Cherenkovs, CEDARs,…
 You can find all that and answer all your questions in two week’s time:
Dry-Run-2 – week 13 (27-31 March)
Full commissioning exercise of the North Area beams
Prepare and test the maximum possible before the beam starts.
New in 2006: BI hardware renovation, CESAR software, FESA-2,
advanced software applications, and all kinds of goodies!!!!
21/03/2003
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Shutdown Lectures 2006 - 75