PowerPoint PresentationY.Furletova (JLAB)
2019 Two accelerator proposals
(ep→ →e’ n X) . Lambda decays
(Λ →p −
J/Ψ, φ
• Saturation (coherent/incoherent
J/ production)
Rapidity gap
Diffraction e+d exclusive J/Psi events with proton or neutron tagging
e+He3 with spectator proton tagging.
e+He4 coherent He4 tagging.
e+Au events with neutron tagging to veto breakup and photon acceptance. ….
IR-related physics requirements
EIC Interaction Region layout
~9 m around the IP is reserved for the central detector
But the far forward and far backward detector components are distributed along
the beam line within ±35 m
Design should be able to operate with different beam energy and high luminosity
Very important to keep full detector integration in sync with the accelerator design
from the early stages on 6
far-forward detectors
far-backward detectors
7
From the installation / integration point of view, this area is
completely independent from the Central detector
Integration with the beampipe for Roman Pots and Off-
momentum Detectors is very important
Detector Detector Position (x,z) Angular
Acceptance Notes
ZDC (0.96m, 37.5m) < 5.5 mrad About 4.0 mrad at ~
Roman Pots (2 stations)
(0.845m, 26m) & (0.936m, 28m)
0.0* < < 5.0 mrad
optics/beam energy, lower bound changes.
Off-Momentum Detectors
spaced)
5.5 < < 20.0 mrad
electron quad.
IP
B0-detectors
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• Warm space for detector package insert located inside a vacuum vessel to isolate from insulating vacuum.
125 mm
Shape and coverage of B0 tracker needs to be further evaluated
(5.5 < < 20.0 mrad)
• Create zero field line at electron beam axis by overlapping large diameter main quadrupole and dipole coils.
Higher granularity detectors needed in
this area ( MAPS) with layers of fast-
timing detectors (LGADs)
for photons detection.
tracker => high background area
Detector maintenance
Roman Pots
() = ())
~2m
is the Gaussian width of the beam, is the RMS transverse beam size. is the emittance.
Low Gain Avalanche Detectors (LGADs): Gain 5-100, Large S/N ratio, 30-50 mm thickness Fast-timing: ~30-50 ps per hit, dominated by Landau fluctuation
AC-coupling allows fine segmentation 100% fill factor AC-LGAD 2mmx2mm strip sensor.
Strip pitch = 100um
to n
s c
a tt
e ri
n g
a n
g le
15 GeV on 100 GeV
15 GeV on 250 GeV
High Divergence
Roman Pots resolution
Angular divergence
Yulia Furletova
• Beam angular divergence • Beam property, can’t correct for it – sets the lower bound of smearing. • Subject to change (i.e. get better) – beam parameters not yet set in stone
• *using symmetric divergence parameters in x and y at 100urad. • Vertex smearing from crab rotation
• Correctable with good timing (~35ps). • With timing of ~70ps, effective bunch length is 2cm ->.25mm vertex smearing
(~7 MeV/c)
Off-Momentum detectors
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Protons that come from nuclear breakup have a different magnetic rigidity than their respective nuclear beam (xL<1)
This means the protons experience more bending in the dipoles.
As a result, small angle ( < 5mrad) protons from these events will not make it to the Roman Pots, and will instead exit the beam pipe after the last dipole.
Detecting these requires “off-momentum detectors”.
B0pf
p
γ*
e
e'
Zero-degree Calorimeter
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For detection of neutrons and photons Acceptance: 0<θ<4.5 mrad (Limited by bore of magnet where the neutron cone has to exit)
• ALICE FoCal • ATLAS/CMS ZDC
p + −
(Br~64%)
protons from Lambda. Significant loss −along
the beam line (FFQs) due to low momentum of
those pions.
Th et
V ]
B0
p
−
−
ZDC
Detecting Lambda’s decays in the target fragmentation area is very hard, due to a very large decay length (meters).
Would require in addition detection of negative charged particles (pi-) at the OFF- momentum detector location
Far-backward (electron-going) region
16
This area is designed to provide coverage for the low-Q2 events
(photoproduction)
Need space for the luminosity detector (ep -> epg bremsstrahlung photons)
Synchrotron photons collimation scheme needs to be further refined
Central detector installation in IP6
STAR detector in the beam position
Hall length ~3200 cm
Hall width ~1615 cm
Door width 823 cm
Door height 823 cm
Limited space along the beam line (the final focusing quads are placed as close
to the IP as possible in order to maximize the luminosity)
Barrel part of the main detector is designed to fit through the door
Use large assembly hall for the long detector maintenance
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Central detector maintenance Short access (hours) – no major disassembly actions
• Electronics trailer
• e/m calorimeter frontend electronics
• B0 magnet detectors (silicon tracker and e/m calorimeter)
• Outer part of the central detector (planar trackers, perhaps the gaseous
RICH electronics, perhaps DIRC electronics – if installed)
Scheduled maintenance (months) – detector moved to the assembly hall
• The only option to access the central tracker and the forward / vertex /
backward silicon trackers
Central detector maintenance Longer access mode for maintenance (endcaps rolled out)
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beryllium beampipe with the
outer diameter 63.5 mm
Few % radiation length material
required angular range
White circle: h = -4.0
Endcap pipe conical part:
White circle: h = 4.0
The HERA and KEK experience show that having backgrounds under
control is crucial for the EIC detector performance
There are several background sources :
primary collisions
beam-gas induced
synchrotron radiation
Background estimation is also a part of an Other Project Cost
activity in experimental equipment
fb-1 (inside the towers); perhaps ~5
less at the SiPM location
-> backward EmCal: ~250 rad/year
(at a “nominal” luminosity
Primary collisions contribute a substantial fraction of the ionizing radiation and low
energy neutron fluence in the experimental hall
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multiplicity events in the central detector apparatus
GEANT4
The GEANT simulation shows that for 10-9 mbar vacuum the contribution of such
events to the data stream is relatively small compared to the physics collisions
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MOLFLOW
Beam-gas induced background
The simulation shows that the EIC detector will obtain annual dose of 6*1010
n/cm2 (1 MeV equivalent) in the Silicon Vertex Tracker. This is more than three
orders of magnitude less than the suggested tolerance of 1014 n/cm2
Beam-gas interactions are also the main source of neutrons that thermalize within
the detector hall and cause the damage.
FLUKA
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Synchrotron radiation Even in a configuration with the crossing angle, incoming electron trajectory
bending in the upstream dipole and quadrupole magnetic fields produces
substantial synchrotron radiation load
The design of absorbers and masks must be modeled thoroughly
18 GeV electron beam 0.26 A
~1 W/cm2
Summary
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The full integration of EIC detectors and IR is crucial for the EIC science. This
has been a large emphasis of the EIC design, and the current configuration
satisfies the requirements.
Constraints coming from the experimental hall layout and the accelerator design
are being taken into account for the physics detector design, as well for its
integration and maintenance.
The detailed detector layout and configuration is driven by the ongoing EIC
community efforts. Work on the detector support structure, services and detector
installation and maintenance is ongoing to ensure there are no surprises.
Experience at HERA and e+e- colliders showed the importance of the control of
backgrounds. Background mitigation is included from the start in the EIC design
(crossing angle, magnet locations, vacuum and beam pipe design). Physics and
background simulations are in a mature state, but continuing vigilance is
required.
We need your help and experience to interface accelerator and detectors!
Backup
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~4 hermetic coverage in tracking, particle ID and calorimetry with the polar
angle acceptance only limited by the beam pipe
Low material budget in the acceptance (at the level of 3-5% X/X0): • To minimize multiple Coulomb scattering for the low-momenta particles
• To minimize bremsstrahlung in front of the e/m calorimeters
Need to integrate the support structures, services and cabling
Start thinking about the assembly, installation and maintenance
EIC central detector outline
constant vacuum 10-9 mbar
Total ~100Gbps
Total ~1Gbps
ZDC resolution
Yulia Furletova Neutron samples from Meson structure group ( for different energies and ZDC granularity 0.6 cm vs 3cm ):
Distance from beam X [mm]
Distance from beam X [mm]
D is
ta n
ce f
ro m
b ea
m Y
e p -> () -> e’ + +
Size of 60x60 cm should be sufficient, high granularity is very important for high-energy operations
e-/e+ ,Z0,W ±
0, +, K0,K+,B0
proton momentum [GeV/c]
to n
s c
a tt
e ri
n g
a n
g le
15 GeV on 100 GeV
15 GeV on 250 GeV
~20 cm
High DivergenceHigh Divergence
High AcceptanceHigh Acceptance
High Divergence: smaller ∗ at IP, but bigger ( = 30) -> higher lumi., larger beam at RP
High Acceptance: larger ∗ at IP, smaller ( = 30) -> lower lumi., smaller beam at RP
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~25 cm
• Only one beam configuration for now. • Acceptance gap still observed. • Lower acceptance at high . • B0 plays largest role at this beam energy.
proton momentum [GeV/c]
to n
s c
a tt
e ri
n g
a n
g le
15 GeV on 100 GeV
15 GeV on 250 GeV
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• Large doorway
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Detector assembly (movie)