PoS(PSTP 2013)005 http://pos.sissa.it/ ∗ detection system. The focus of the COMPASS experiment is the study of hadron structure and [email protected] π Speaker. The Bochum/Bonn polarized target groupat is CERN involved in and the in fixed baryon targetare spectroscopy experiments focused at COMPASS ELSA on and the MAMI. study4 The of experiments the at nucleon Bonn resonance and regionhadron Mainz spectroscopy with with polarized high beam intensive and muon target andIn with hadron this beams. a proceeding technicalTarget achievements will and be highlighted. operation New experience developments tocoil of produce for the an continuous internal Bonn superconducting DNP Frozen polarizing willBochum Spin be NMR shown. system will In be presented. addition the setup and measurements with the new ∗ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c ⃝ XVth International Workshop on Polarized Sources, Targets,September and 9-13, Polarimetry, 2013 Charlottesville, Virginia, USA Gerhard Reicherz Ruhr -Universität Bochum, D-44780 Bochum, Germany E-mail: Recent research activities and results ofBochum/Bonn the Polarized Target Group PoS(PSTP 2013)005 Gerhard Reicherz ]. ]. 1 2 2 . The aim is to understand the strong interaction in 1 -Continuous-Mode-Target” is the combination of the high angular π Collaborative Research Center 16 The aim of the project “4 The frozen spin target is a powerful tool for polarization experiments at low intensity beams The experiments are performed at the electron accelerator ELSA at Bonn. The goal is to gain a The Standard Model of the strong, electromagnetic and weak interaction is in general very 1 acceptance of the Frozen-Spin-Mode with thepurpose high a polarization cryostat-internal of polarizing the magnet Continuous-Mode.spin of For the mode, this size is of the needed.concept holding will coil, In be as described. the used in following the the frozen Bonn development of the “Inversed Notched Coil" 3.1 Internal magnet development 3. Polarized target developments but the price for thepolarize-up good or acceptance repolarize is the on targetthe one material, detector hand and and external a on polarizing loss another magnet in a for beam the dedicated polarization time, railway procedure[ caused system by to the move need to good understanding of the spectrum andunderlying the QCD properties dynamics of in baryon the resonances photoproductionof and of to mesons mesons. investigate the Furthermore, are in-medium investigated. properties the Crystal To Barrel/TAPS perform and the theseof BGO-OD experiments a experiment. two polarized The detector beam polarizedpossible. systems make target the are Polarization and observables measurement available, the are of availability from of highly the decisive sensitive importance data. double for polarization an Thewhich extraction observables spectroscopy are of of performed the to baryon resonances unravel resonancesinvestigated the in ask properties a for of dedicated double the multi-channel pertinent polarization partialdata wave resonances. experiments, sets. analysis The These together highly data with complex many are subjectof other further of experiment, available the theory CRC and 16 partial-wave analysis can as only well be as advanced instrumentation by [ a close cooperation 2. Physics programm Bonn CB-ELSA well established. Until recentlywas the the Standard search Model for still theand had Higgs understanding two Boson open of at ends. the highestpossible different energies On existence of and forms the the on one of Higgs the sidemechanism strongly boson other it was is interacting side recently responsible matter. it reported for by isexplains the First the the only LHC a formation evidence creation experiments. few for percent of The of the the Higgs The the rest mass masses of of the of the mass nucleons quarks is andone due therefore and to can of leptons. the the understand strong matter the interactions surrounding spectrum itself. However, us. (hadrons) and The this is question the the how properties this central of happens subject and the of how emerging the strongly CRC interacting 16 particles Bochum/Bonn Polarized Target Group 1. Introduction the non-perturbative regime. PoS(PSTP 2013)005 ]. 5 4, which is − e Gerhard Reicherz 4 mm, otherwise ≪ . 0 B / B 5 T at a current of 90 A. ∆ . - signal is blanked by the ringing 2 this point is plotted. For comparison the 1 3500 total windings. The use of a multi-filament 3 ∼ deuterons. In comparison a solenoid of the size (and 9 T. In Fig. . 1 and = 0 B 254 mm) is needed to create a magnet field of 2 . 0 = ]. The "Liverpool-box" is not available any more. The schematics have to be 6 18 correction windings with × 5 T is used. In the target region this has a field homogeneity of . 2 = Free Induction Decay The advantage of pulsed-NMR is a fast signal detection and a good signal to noise ratio. The To determine the absolute value of the target polarization, continuous wave nuclear magnetic Such a test coil was constructed on a winding apparatus specifically designed for this purpose. A measurement of the critical current at 4.2 K was successfully carried out. It lies at approx- A manufacturing feasible possibility is the use of correction windings placed on the solenoid For dynamic polarization in the Continuous-Mode a large, external magnet with a flux density 2 B measuring time plays a minor role.should To be determine the saturated polarization so only thatratio. a the small The amount polarization main of motivation will to the be prefer spins pulsed-NMR CW-NMR preserved instead after but of applying the this the pulsed-NMR reduces RF-pulse technique a is theof short that signal the for part to the of pulse. noise the FID During this time (few micro seconds) an important part of quadrupol broadened superconductor (Ø resonance (CW-NMR) is the current method of choice.45 The years development of ago. the first The Q-meter started in so the called "Liverpool-box", early which 80s is [ changed, still due to the the standard fact Q-meter, that was awas developed. few developed circuit The components module and are its obsolete. performanceor For will replacement medicine be a pulsed-NMR presented. new is In RF-part the other sciences usual like technique. chemestry 3.2 Polarization detection The coil has 2 The total thickness in the region of the correction windings is approximately 2 imately 71 A with a central field of The projection of this fitpossible to to reach 1 a K current gives of an 100 estimation A, which that is at over the the required working 90 temperature A. it should be (“Notched Coil"’). In can be shownwith however regards that to to the meet positioning thethe in homogeneity positioning condition this can the case not tolerance is be very metcoils small. due of to In a the construction lack the “Inversed of tolerancethe guidance Notched criteria of coil Coil” for the carrier coil are these wire. situated In windingsdeterioration within contrast of can the the the be correction field solenoid. optimally homogeneity are positioned, minimized. Through so two that notches winding in errors and resulting of Bochum/Bonn Polarized Target Group needed to dynamically polarize protons the thickness is smaller than 2 mm. data supplied by the wire manufacturer is plotted and fitted by the function given by Bottura [ thickness) of an internal holdingvolume coil is has a small. small Such totalbe magnetic a volume corrected. magnet and no the In longer ratio addition, fulfilsdetection to the threshold the the total of target homogeneity the thickness conditions particles of and producedmaterial. the the in magnet field the experiment must must increases be with kept the small, thickness of as the the energetic PoS(PSTP 2013)005 2 ], / 4 , λ (3.1) (3.2) 3 × n Gerhard Reicherz and a coaxial transfer 80% are reached [ d ]. 8 ≥ A dyn π P . For the excitation of the spin N 2 2 ¯ hI N -method. The area under the line 2 3 µ 2 g 1538. The linearity of the Q-meter must ≡ TE ]. TE = ω 9 P AU , d 7 0 × ω 052 ω . ) 0 4 dyn / ω ( 80 AU χ 100 nH is applied with a high filling factor. Usually ∞ ≥ ≥ = 0 ∫ E dyn π P must be huge compared to the impedance of the series reso- N 2 ¯ hI N cc 2 µ 2 g ). Maximum polarizations values of 4 = P 4 to minimize its influence on the circuit. The capacitor is mechanically / λ = 0.052% (Fig. ] in proton and deuteron rich versions. Typical magnetic fields are 2.5 to 5 Tesla, hence 11 TE , P 4 , 3 Thermal Equilibrium For instance the deuteron polarization at a magnetic field of B = 2.5 T and a temperature of T The calibration of the CW-NMR is performed by the TE The resonance circuit has to be changeable or should be tuneable in this frequency region. Due As target materials like alcohols, ammonia, carbon hydrogen and lithium-hydrogen are mainly The minimum components of a Q-meter are shown in Fig. The constant current resistor R 3 shape is proportional to theknown polarization. polarization the Therefor proportional by factor measuring can be the calculated: area units of a signal with a = 1 K is The thermal equilibrium polarization for avia given the magnetic Brillouin field function. and temperature can be calculated the proton coil consists of one winding with a reduced filling factor. The transfer cable is to the very small deuteron signal a coil of used [ the resonance frequencies are between 10 MHz and 250 MHz. or voltage variably tuned toorder the to adequate increase Larmor the frequency. signal Forinputs to phase of noise sensitive the ratio, measurement, phase the in sensitive phase detector cable (Mixer: is load varied and to reference zero signal)[ phase between the two corresponding to an enhancement factor be constant over a huge range of a factor of up to (2000:1). 3.2.1 CW-NMR Bochum/Bonn Polarized Target Group signal vanishes and a deformed signalfor results determination after of the the Fourier polarization transformation, is thus not a possible line [ shape fit nance circuit, which consists ofcable a between variable the capacitor, ’warm’ part a and dumping thearound resistor induction the coil, R target placed material. in the The cryostat polarization atfactor changes low Q the temperature of inductance in of or the the resonance coilplified circuit with and changes that measured and the quality with this a resultsthe diode in area or a under phase voltage the variation sensitive line which detector. shape will The is be integrated proportional am- to signal the and polarization: therefore or much shorter than transition, a RF-signal generator is utilized.the For magnetic the field dynamic must nuclear be polarization constant,line - there to process for detect (DNP) the the RF-frequency whole must absorption be signal. varied over the resonance PoS(PSTP 2013)005 , Gerhard Reicherz , Prog. Part.Nucl. , Nucl. Instr. Meth., Nucl. Instrum. and Meth. A Nucl. Intr. Meth., A398 (1997) 109-125. , Applied Superconductivity, IEEE the result is presented with a linear fit. The Particle Detection 3 π 5 He Targets for Particle Physics Experiments 3 ˝ U1057. ]. 12 Recent Progress in the Nuclear Polarization of Solid Deuterated Butanol Targets , Pulsed NMR for the determination of the nuclear polarization The development of NMR techniques for the high precision measurement of target A New Frozen-Spin Target for 4 10 Polarized H, D and A line-shape analysis for spin-1 NMR signals The development of NMR techniques for the high precision measurement of target , Nucl. Instr. Meth., A 526 (2004) 65-69. , Nucl. Instr. and Meth. A 324 (1993) 433. A practical fit for the critical surface of NbT shows a thermal equilibrium signal of D-butanol at 1 K and 2.5 T. 4 A 526 (2004) 96-99 G. Reicherz et al.: G.R. Court: polarisation Phys. 49 (2002) 403-489 J. Heckmann et al.: Appl. Magn. Reson. 34 (2008) L. Bottura: G.R. Court et al.: polarisation C.M. Dulya: St. Goertz et al.: A. Thiel et al. (CBELSA/TAPS Collaboration) Phys. Rev. Lett.C. 109, Bradtke 102001 et (2012). al.: Transactions on 10.1 (2000) 1054 436 (1999) 430-442. This work is supported by the EU Seventh Framework Programme (HadronPhysics3). The concept of the “Inversed Notched Coil" minimizes the positioning error of the correction In Fig. To determine the linearity of the Q-meter a reference circuit was adapted and the circuit signal The RF-part is built of splitters, amplifiers and attenuators on a four-layer circuit board. The [9] [6] [7] [8] [4] [5] [1] [2] [3] References slope had an accuracy of 0.6%excitation voltages at [ which the main error results from the measurement of the small coils on the solenoid andlarization fulfils of the deuterons homogeneity possible. condition By thatbe using must keep a be very superconducting obtained thin. wire to the The make thicknessat first the of 4.2 prototype po- the K. built A magnet in measurement can Bonn of fulfillsestimation the of the field the expectations is critical for current. in the progress. A criticalbeen new Further current developed continuous tests to wave at replace nuclear 1 the magnetic K Liverpool-box. resonance Q-meter are has planned to confirm the was attenuated in a range of +3 to -11dB. In Fig. 4. Summary tuning box is externally connected viaRF SMA to connector to LF-converter provide with a diode very andfour-layer flexible mixer board. arrangement. for The a The phase linearity sensitive measurementsfurther detection amplification. are was performed newly without designed on dc-offset a compensation and Bochum/Bonn Polarized Target Group 3.2.2 Q-meter PoS(PSTP 2013)005 , Gerhard Reicherz , Masterthesis 6 , Nucl. Instrum. and Meth., A 694 (2012) 69-77 Entwicklung einer HF-Messschaltung zur Polarisationsdetektion Measurement of electron spin-lattice relaxation times in radical doped butanol samples A continuous wave NMR system for detection of the polarization of solid targets Ruhr-Universitiy Bochum (2013) G. Reicherz: C. Hess et al.: H. Vondracek: at 1 K using the NEDOR method Proceedings PSTP 2011, St. Petersburg (2011) 135-138 [11] [12] Bochum/Bonn Polarized Target Group [10] PoS(PSTP 2013)005 Gerhard Reicherz 7 Minimum components of a Q-meter Figure 2: Critical current in dependence of the magnetic field at 4.2 K and 1 K. Larmor frequencies for protons and deuterons at different magnetic fields Figure 1: Table 1: HH 16.3 MHz 106.3 MHz 22.8 MHz 148.8 MHz 32.6 212.6 MHz MHz Nuclei2 B=2.5T1 B =3.5T B=5T Bochum/Bonn Polarized Target Group PoS(PSTP 2013)005 Gerhard Reicherz 8 TE-signal vs RF input power from PSD 3 TE signal of D-butanol at T = 1K and B = 2.5 T Area units of NH Figure 4: Figure 3: Bochum/Bonn Polarized Target Group