Hendrik Hähnel

• Dr.
• PostDoc Position at Goethe University Frankfurt

Motivated by the necessary replacement of the GSI UNILAC poststripper linac, a compact and efficient linac design based on IH-type cavities has been developed. Using KONUS beam dynamics, it was possible to design a linac consisting of only five cavities that can be operated by the existing UNILAC RF amplifier structure. The transversal focusing sch...

The combined zero degree structure (KONUS) is a quasiperiodic structure. It was developed for the low-energy part of multigap drift tube linacs with H-type cavities. Their rf efficiency depends very much on a low electrical capacity of the drift tube structure, while in E-type structures like the Alvarez-DTL this is a minor effect. Therefore, inste...

The FAIR proton linac is developed as the high current proton injector for the future FAIR antiproton production chain at GSI. It will provide a 70 mA proton beam at an energy of 68 MeV to the SIS18 synchrotron. The linac consists of an ECR ion source, followed by a ladder RFQ and a normalconducting linac based on CH-type cavities. High beam curren...

The Low Energy Beam Transport line (LEBT) for the Frankfurt Neutron Source (FRANZ) has been redesigned to accommodate a 60 keV proton beam. Driven by a CHORDIS ion source, operating at 35 kV, a newly designed electrostatic postaccelerator has beeen installed to reach the desired beam energy of 60 keV. Additional upgrades to the beamline include two...

Additive manufacturing (AM) of metals has the potential to provide significant benefits for the construction of future particle accelerators. The combination of low cost manufacturing of complex geometries in combination with efficiency gains from improved linac design enabled by AM may be one way towards future cost-effective green accelerator fac...

To satisfy the beam requirement of the KoBRA experiment (0.5 nsec in 1σ), rebunching is required in the energy range up to 15 A MeV and for particles with an A/q range from 1 to 7. In cooperation with IBS and Hanmac Corporation, BEVATECH proposed a five-gap IH-buncher cavity which has excellent bunching properties from 5 to 15 MeV/u. Main challenge...

Miniature single-board cameras have been used in our group for several years to monitor beam-induced residual gas fluorescence. This work shows new test results of Raspberry Pi cameras, in use with high energy beams. These devices are installed in vacuum at hard-to-reach locations. They have been tested in strong magnetic fields with low energy pro...

A prototype of a beam-induced residual gas fluorescence monitor (BIF) has been developed and successfully tested at the Institute of Applied Physics (IAP) at the Goethe University Frankfurt. This BIF is based on ten single-board cameras inserted into the vacuum and directed onto the beam axis. The overall goal is to study the beam with tomography a...

Additive manufacturing ("AM" or "3D printing") has become a powerful tool for rapid prototyping and manufacturing of complex geometries. A 433 MHz IH-DTL cavity has been constructed to act as a proof of concept for additive manufacturing of linac components. In this case, the internal drift tube structure has been produced from 1.4404 stainless ste...

Additive manufacturing (AM or “3D printing”) has become a powerful tool for the rapid prototyping and manufacturing of complex part geometries. Especially interesting for the world of particle accelerators is the process of the 3D printing of stainless steel (and copper) parts. We present a first prototype of a 43 MHz IH-type linac cavity with an i...

Additive manufacturing (or "3D printing") has become a powerful tool for rapid prototyping and manufacturing of complex geometries. As technology is evolving, the quality and accuracy of parts manufactured this way is ever improving. Especially interesting for the world of particle accelerators is the process of 3D printing of stainless steel (and...

The continued popularity of miniaturized cameras integrated into smartphones is leading to further research for more advanced CMOS camera sensors. This made CMOS technology even superior to scientific CCD cameras. Due to the lower power consumption and high flexibility, a multi-camera system can be developed more effectively. At the Institute of Ap...

The Nuclotron ring of the NICA project will get a new light ion injector linac (LILac) for protons and ions with a mass to charge ratio up to 3. The LILac will consist of 2 sections: A 600 keV/u RFQ followed by an IH-type DTL up to 7 MeV/u, and a postaccelerator IH cavity for protons only-up to 13 MeV. A switching magnet will additionally allow 13...

Additive manufacturing (or "3D printing") has become a powerful tool for rapid prototyping and manufacturing of complex geometries. As technology is evolving, the quality and accuracy of parts manufactured this way is ever improving. Especially interesting for the world of particle accelerators is the process of 3D printing of stainless steel (and...

The MYRRHA project aims at coupling a cw 600 MeV, 4 mA proton linac with a sub-critical reactor as the very first prototype nuclear reactor to be driven by a particle accelerator (ADS). Among several applications, MYRRHA main objective is to demonstrate the principle of partitioning and transmutation (P&T) as a viable solution to drastically reduce...

For the production of Antiproton beams with sufficient intensities, a dedicated high-intensity 325 MHz Proton linac is currently under construction. The Proton linac shall deliver a beam current of up to 70 mA with an energy of 68 MeV for injection into SIS18. The source is designed for the generation of 100 mA beams. The Low-Energy Beam Transport...

The construction of a 3.3 m Ladder-RFQ at IAP, Goethe University Frankfurt, has been finished successfully last summer. This RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac [1, 2] at FAIR 1 [3]. Along the acceleration section the parameters modulation, aperture and synchronous phase are...

The MYRRHA project aims at coupling a cw 600 MeV, 4 mA proton linac with a sub-critical reactor as the very first prototype nuclear reactor to be driven by a particle accelerator (ADS). Among several applications, MYRRHA main objective is to demonstrate the principle of partitioning and transmutation (P&T) as a viable solution to drastically reduce...

An efficient and compact linac design proposal for the UNILAC poststripper based on H-mode cavities and KONUS beam dynamics has been developed at IAP Frankfurt in the last few years [1, 2]. It features five RF-cavities with high shunt impedances. The total length of the proposed poststripper linac is 22.8 m.

The GSI UNILAC will serve as the main injector for the upcoming FAIR project. Since the existing Alvarez DTL is in operation for more than 40 years, it has to be replaced to ensure reliable operation in the future. To this purpose a compact and efficient linac design based on IH-type cavities and KONUS beam dynamics has been designed at IAP Frankfu...

A collaboration of SCK•CEN, IAP and BEVATECH GmbH is currently constructing the room temperature CH section of the 16.6 MeV CW proton injector for the MYRRHA project. The elaboration of all the construction readiness files for the construction of the accelerating cavities of the first CH section (1.5 to 5.9 MeV) is ongoing. In parallel, the plannin...

The 'Combined Zero-Degree Structure' ('Kombinierte Null Grad Struktur - KONUS') beam dynamics concept has been successfully applied on several linacs, some of them in routine operation since decades. However, the KONUS lattice parameters optimization is often done in a results-oriented approach, depending on the designers' experience. This paper fo...

We propose an efficient design for heavy ion acceleration from 1.4 to 11.4 MeV/u with a design current of 15 emA for a U 28+ beam as a possible injector for FAIR. The proposed linac is based on IH-DTL cavities and quad-rupole triplet focusing. The KONUS beam dynamics concept is used to achieve high acceleration efficiency. By optimization of the tr...

For its role as dedicated injector for FAIR, several sections of the UNILAC have to be upgraded for high current uranium operation. The Alvarez linac in the poststripper section of the UNILAC is in operation since more than 40 years and therefore a replacement by a new linac would be beneficiary to FAIR operation. We propose an IH-DTL linac as repl...

A 2MeV proton beam will produce a quasi-Maxwellian neutron spectrum of around 30 keV by the 7Li(p, n)7Be reaction. The experiments are mainly focused on the measurement of differential neutron capture cross sections relevant for the astrophysical s-process in nuclear synthesis. Moreover, proton capture cross sections for the astrophysical p-process...

The UNIversal Linear Accelerator (UNILAC) at GSI serves as injector for all ion species from protons to uranium since four decades. Its 108 MHz Alvarez type DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue. The DTL will be replaced by a completely new section with almost same design parameters, i.e. pulsed...

The UNIversal Linear Accelerator (UNILAC) at GSI serves as injector for all ion species from protons to uranium since four decades. Its 108 MHz Alvarez type DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue. The DTL will be replaced by a completely new section with almost same design parameters , i.e. pulsed...

The UNIversal Linear Accelerator (UNILAC) at GSI has served as injector for all ion species from protons for uranium for the past four decades. Especially its 108 MHz Alvarez type DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue. The DTL will be replaced by a completely new section with almost the same desi...

We propose a new design for the MEBT section of the High Current Injector (HSI) at the GSI UNILAC as part of the planned UNILAC upgrade for the FAIR project. The existing MEBT section was designed in 1996 and was based on a novel concept called the superlens (SL) which uses a magnetic quadrupole doublet lens combined with an 11-cell RFQ cavity for...

The High-Energy (HE) Linac is proposed to substitute the existing UNILAC post-stripper section. The post-stripper is an Alvarez DTL, which is in operation over four decades successfully. A quasi Front-to-End simulation along the UNILAC shows that by taking future upgrade options into account already, with the existing Alvarez section the FAIR requi...