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| TUPAF088 | Final factory-side Measurements of the Next SC CH-Cavities for the HELIAC-Project | 943 |
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Funding: Work supported by the EU Framework Programme H2020 662186 (MYRTE); Work supported by BMBF Contr. No. 05P15RFBA; The upcoming FAIR project (Facility for Antiproton and Ion Research) at GSI will use the existing UNILAC (UNIversal Linear Accelerator) as an injector to provide high intensity heavy ion beams at low repetition rates. As a consequence a new superconducting (sc) continous wave (cw) high intensity heavy ion Linac is required to provide ion beams above the coulomb barrier to keep the Super Heavy Element (SHE) physics program at GSI competitive on an international level. The fundamental Linac design comprises a high performance ion source, the High Charge State Injector (HLI) upgraded for cw-operation and a matching line (1.4 MeV/u) followed by a sc Drift Tube Linac (DTL). Four cryo modules each equipped with three Crossbar-H-mode (CH) structures provide for acceleration up to 7.3 MeV/u. The first section of this ambitious accelerator project has been successfully commissioned and tested with heavy ion beam from the HLI in 2017. It comprises two sc 9.3 T solenoids and a sc 217 MHz CH-cavity with 15 equidistant gaps as a demonstrator. The construction of the next two sc 217 MHz 8 gap CH-cavities is nearly finished and final factory-side measurements will be presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF088 | |
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| TUPAK002 | Advanced Approach for Beam Matching along the Multi-Cavity SC CW Linac at GSI | 955 |
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| A multi-stage program for the development of a heavy ion superconducting (sc) continuous wave (cw) linac is in progress at HIM (Mainz, Germany) and GSI (Darmstadt, Germany) under support of IAP (Frankfurt, Germany). In 2017 the first section of the CW-Linac has been successfully commissioned at GSI. Beam acceleration at the CW-Linac is foreseen to be performed by up to twelve multi-gap CH cavities. The linac should provide the beam for physics experiments, smoothly varying the output particle energy from 3.5 to 7.3 MeV/u, simultaneously keeping high beam quality. Due to a wide variation of the input- and output -beam energy for each cavity, a longitudinal beam matching to every cavity is of high importance. An advanced algorithm for an optimization of matched beam parameters under variable rf-voltage and rf-phase of each cavity has been developed. The description of the method and the obtained results are presented in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK002 | |
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| TUPAK003 | Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI | 959 |
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Funding: Work supported by BMBF Contr. No. 05P15RFBA and EU Framework Programme H2020 662186 (MYRTE) For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of Ea = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK003 | |
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| TUPAK004 | Superconducting CH-Cavity Heavy Ion Beam Testing at GSI | 962 |
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| Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI- High Charge State Injector. The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK004 | |
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| WEPAL024 | High Precision Beam Parameter Stabilization for P2 at MESA | 2209 |
| SUSPL056 | use link to see paper's listing under its alternate paper code | |
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Funding: Cluster of Excellence PRISMA (EXC 1098/2014) German Research Foundation DFG (GRK 2128) The experiment P2 will measure the weak mixing angle with an all-time high precision via electron-proton scattering. The measured physics asymmetry and its uncertainty has to be corrected by the apparatus' asymmetry, which is generated by helicity correlated fluctuations of the beam parameters position, angle, intensity and energy. This Poster will describe how the high precision of 0.1 ppb of the parity violating asymmetry can be provided by the high precision measurements of the parameters position, angle and intensity. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL024 | |
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| WEPML045 | Infrastructure for Superconducting CH-Cavity Preparation at HIM | 2796 |
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| A superconducting cw LINAC for heavy ions is currently under development at GSI in Darmstadt and HIM in Mainz. This Linac is based on 217 MHz multigap bulk niobium Crossbar H-mode RF-cavities. In order to treat and prepare RF-cavities with such a complex geometry a new cleanroom facility has been already built at the Helmholtz-Institut in Mainz. All tools and machines inside the cleanroom can handle cavities with up to 800 mm in diameter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, respectively it features a large ultrasonic and conductance rinsing bath, a high pressure rinsing (HPR) cabinet and a vacuum oven. The HPR cabinet has an inside clearance of 1.4 m. The large cavities sit on a rotating table, while the rising wand moves vertically up and down. Due to the crossbar structure of the RF-cavities the HPR device allows for off axis-rinsing in their quadrants. For RF testing a 52 m² (4 m x 13 m) concrete shielded area with sufficient liquid helium and nitrogen supply is located next to the cleanroom and the cryo-module assembly area. We will report on the new SRF infrastructure in Mainz and the commissioning of the new high pressure rinsing cabinet. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045 | |
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| THPMF062 | Smith-Purcell Radiation for Bunch Length Measurements at the Injection of MESA | 4213 |
| SUSPF021 | use link to see paper's listing under its alternate paper code | |
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Funding: Federal Ministry of Education and Research MELBA is a test apparatus for the injector of the energy recovering, superconducting accelerator MESA in Mainz. A chopper-buncher system containing two circularly deflecting cavities and a first and second harmonic buncher cavity have been built. They serve to produce short bunches with a longitudinal extension < 600 μm (one degree of RF-phase) in the longitudinal focus for beam currents of up to 10mA. We intend to use Smith-Purcell Radiation (SPR) to test this arrangement. SPR is generated if a charged particle passes close to a periodic metallic structure, e.g. a grating. The signal has a coherent part which increases its intensity quadratically with the bunch charge if the bunch length is smaller than or comparable to the grating period. Different gratings can be placed below the electron beam to determine the length of the electron bunches. This measurement is non-destructive. The generated THz radiation will be observed with a bolometer cooled down to 4.2K which offers sufficient sensitivity in our regime of operation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF062 | |
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| WEPAL023 | Pulsed Operation at MAMI with High Beam Loading | 2206 |
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Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate The Mainz Microtron Accelerator (MAMI) is a microtron cascade which is normally operated CW for particle physics experiments. For certain investigations it is necessary to use a pulsed beam (macro pulses, several milliseconds). Up to now this pulsed mode can only be applied if the beam loading for the accelerating RF structures is negligible. To achieve higher pulse intensities the accelerator RF infrastructure needs to be equipped with feed-forward techniques to compensate for the expected beam loading. To monitor beam losses the machine protection system at MAMI needs to be extended to be able to localize fast occurrences of beam losses. This paper will present the possibilities being investigated to allow pulsed operation of MAMI within the near future. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL023 | |
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