Polarimeters in Other Research Groups

This page records polarimeters and closely related polarization-detection systems that are most relevant to the present project. The emphasis is on hadron, deuteron, proton, and neutron programs. When a hardware detail cannot be stably confirmed from public primary sources, I mark it as unconfirmed instead of treating it as settled fact.

RIKEN RIBF#

dPol#

Role: a beam-line polarimeter on the IRC bypass beam-transport line, used to monitor polarized deuteron beams before injection into the SRC.
Reaction: public accelerator and experiment-layout materials consistently describe it as using d-p elastic scattering; the 2017 layout slides explicitly state 90 MeV/nucleon.
The publicly accessible information that I could verify is mostly limited to accelerator and layout slides; I did not find a detector note as detailed as the one available for BigDpol.
Unconfirmed detail: some secondary notes associate H1161 / H1161GS with dPol, but I did not find a sufficiently stable primary public source for that assignment, so I do not present it here as established fact.

Resources#

BigDpol#

BigDpol sketch

Role: installed on the SRC extraction beam line for d-p elastic-scattering polarimetry in the 190-300 MeV/nucleon range.
The clearest public detector note I found is in RIKEN Accel. Prog. Rep. 42: BigDpol consists of a target chamber, a 2 mm alumina cone window, and four symmetrically placed pairs of plastic scintillators.
Scintillator: BC408.
PMT: Hamamatsu H7415.
Geometry: scattered deuterons and recoil protons are detected in kinematical coincidence in the left / right / up / down directions; the quoted opening angle is about 10°-70°. The sketch also shows approximate R620 and R770 radial labels, which are useful as indicative deuteron / proton arm distances.
Target: polyethylene (CH2).

Resources#

KuJyaku#

Purpose: developed for d-p elastic-scattering and spin-correlation measurements with a polarized proton target, covering the cross-section minimum region at 100 MeV/n and 135 MeV/n.
Azimuthal coverage: detector groups are arranged around the beam axis at 0°, 90°, 180°, and 270°.
Magnetic field: the public thesis describes operation together with a triplet-DNP polarized proton target under a typical field of about 0.4 T.
The thesis gives the following representative plastic detectors:

detector	scintillator	size (mm^3)	PMT	distance from target (mm)
Pl_p	BC-408	70×70×25	H7195	1000
Pl_d	BC-408	250×70×10	H7195	950

Resources#

JINR / Nuclotron / DSS#

DSS (Deuteron Spin Structure) is one of the core internal-target spin experiments in the Nuclotron / NICA program, using polarized deuteron and proton beams to study spin-dependent observables.
The early Nuclotron ITS polarimeter is reasonably well documented in public notes: it was based on backward-angle d-p elastic scattering, with early proton and deuteron plastic counters of about 14×20×20 mm^3 and 20×20×20 mm^3, respectively, placed roughly 60 cm from the target.
In later DSS papers and conference materials, the implementation usually appears as a segmented plastic-scintillator setup with PMT readout; if one only wants the currently cited readout hardware, H7416MOD appears repeatedly in several conference notes.
One recent upgrade direction is to extend part of the plastic-counter readout from PMTs to SiPMs.

Resources#

Forschungszentrum Julich / COSY#

EDDA#

EDDA was one of the early major hodoscopes at COSY, originally built for pp elastic-scattering excitation functions and spin-observable measurements.
For a long period before and around the JEDI / EDM program, the EDDA plastic-scintillator system was also used as a beam polarimeter.
In the present context, EDDA matters mainly as the direct predecessor of later COSY JEDI / JePo polarimetry.

Resources#

JEDI polarimeter / JePo#

JePo is a newly designed dedicated beam polarimeter for EDM searches, intended to replace EDDA.
The public JARA description gives the core concept clearly: a modular calorimetric polarimeter based on LYSO modules of about 3×3×8 cm^3, coupled to large-area SiPM arrays.
The detector has radial symmetry and is geometrically optimized for up-down and left-right asymmetry measurements.
The JINST paper gives the full system description: 52 LYSO modules arranged in four symmetric blocks (up, down, left, right), with plastic scintillators in front for dE/dx particle identification.
Main application: long-term, high-stability polarization monitoring for proton and deuteron EDM searches in the COSY ring.

Resources#

Jefferson Lab (cross-domain reference)#

This section is kept mainly as a cross-check. JLab polarimetry is for electron beams rather than hadron beams, but its beamline instrumentation is documented very well and is useful when comparing dedicated polarimeters with related detector systems.

Hall A Moller polarimeter#

Purpose: measurement of longitudinal electron-beam polarization.
Principle: the electron beam hits a magnetically saturated thin iron foil, and the spectrometer system selects scattered Moller electron pairs in coincidence.
The Hall A manual explicitly states a target field of about 3 T and electron-pair detection over 75° < theta_CM < 105°.

Resources#

BigHAND#

BigHAND is a large-area neutron detector, not a dedicated beam polarimeter.
I keep it here only as an example of hardware that is often discussed alongside polarized-neutron and Hall A spin experiments.
Public documentation describes it as a layered steel plus thick-plastic-scintillator-bar detector used for neutron detection and TOF-based discrimination.

Resources#

Other relevant hadron polarimeters#

NPOL3 (RCNP, Osaka)#

NPOL3 is a high-resolution neutron polarimeter for polarization-transfer measurements.
The standard configuration described in the NIMA paper is:
first two planes: 20 sets of one-dimensional position-sensitive plastic scintillators, each about 100×10×5 cm^3, covering 100×100 cm^2;
final plane: a 100×100×10 cm^3 two-dimensional position-sensitive liquid scintillator for double-scattered neutrons or recoil protons.
The representative neutron energy is around 200 MeV, with a typical quoted energy resolution of about 300 keV.
It is not a deuteron beam polarimeter, but it is a very useful reference system for hadron polarimetry and polarimeter optimization.

Resources#

SiPM / PMT quick comparison#

This final section keeps only the points that are most relevant for polarimeter design choices, rather than turning into a full device review.

item	PMT	SiPM	practical note
gain	typically 10^6-107	typically 10^5-107	both can reach single-photon amplification
active area	very large single-channel area is possible	single die is smaller and often tiled into arrays	PMT still has an advantage for very large-area coverage
magnetic-field tolerance	sensitive	essentially immune	SiPM is more natural in compact or high-field layouts
operating voltage	high voltage, typically kV	low voltage, typically tens of V	SiPM simplifies power and safety
dark noise	generally lower per unit area	room-temperature DCR is higher	SiPM often needs temperature control and calibration
timing	ns class; MCP-PMT can be much better	tens to hundreds of ps are possible	both can serve TOF well, but through different design routes

If the experiment has ample space, weak magnetic fields, and a need for large single-channel coverage, PMTs remain the more direct option.
If the experiment is compact, operates in magnetic fields, or needs fine segmentation at low voltage, SiPMs are often the cleaner choice.
JePo uses SiPM readout, whereas BigDpol, KuJyaku, and traditional DSS-style systems mostly use plastic scintillators plus PMTs. That transition is itself a useful design trend to keep in mind.

References#

Last update: 2026-03-18
Created: 2026-03-18