Ex: The Muon Campus§ Delivery Ring has same

circumference (slightly larger) than Booster

• ~500 m

§ 8 GeV protons from Booster to Recycler/Main Injector; manipulate bunches to create time structure appropriate for g-2, Mu2e

§ Use (not use) target station for g-2 (Mu2e)

§ Fast extract (g-2) or slow spill (Mu2e) particles from DR to experiments

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Muong-2

Mu2e

TargetStationMainInjector/Recycler

DeliveryRing

Booster

Muon Campus Map

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oldTevatrontunnel…

Beam Transport Lines

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The Delivery Ring§ Originally, the antiproton source during the Tevatron operation § Total circumference ~500 m

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Here, µ is the phase advance per cell, L is the half-cell length and ș is the total bend per half-cell. The DR arcs are comprised of 60o cells, L = 4.4323m and ș = 0.09520.

RESULTS DR lattice functions at ߛ௧ ൌ ǤͶ and 10.03 appear in

Fig 1. The unperturbed lattice is shown at the top, and the lattice with the ߛ௧ quads energized at the bottom. The single strength arc quads q are shown as blue circles, and the double strength straight section quads are red. Fig-ure 2 shows how ߛ௧ varies as a function on the arc quad-rupole integrated strengths.

Figure 1: Lattice functions of the Delivery Ring in the unperturbed machine (top), and at injection (bottom). Transitionߛ��௧ ൌ ǤͶ and 10.04, respectively. Blue and red circles indicate sites of the arc and straight section ߛ௧-quads, respectively.

Figure 2: Variation of ߛ௧ with arc ߛ௧-quad strength.

Maximum dispersion in the arcs is unaffected by the q’s but the rms value is reduced from 1.42 to 1.09 m. Horizontal beta, by contrast, grows from 15.1 to 94.9 m, which should still be acceptable. For a 15 ʌ mm-mr (95%) normalized emittance beam at 8.89 GeV/c (emit-tance at Booster Ring extraction), 3ߪ�ൌ�15 mm or ~0.6 in. This is to be compared to DR quadrupole and dipole half-apertures of 1.75 in. & 1.18 in., respectively. Table 1 lists the variation of the 99% beam envelope over the entire deceleration range that theߛ�௧-quads are energized.

Table 1: Variation of ߛ௧, ȕmax, and the 15ʌ 99% Beam Envelope with Strength q of the Arc Quadrupoles

At injection energy andߛ�௧ = 10.03, the arc Ȗt-quads’ in-tegrated strengths are ~2.1 T-m/m (double that for the nQ07 straight section quads). These quadrupole strengths required are beyond what can be expected from trim magnets. The proposed solution is to shunt current in-to/around the existing magnets at these 18 locations. The nominal injection gradient of the SQC quads is 10.46 T/m. Implementing this scheme requires the nQ07, nQ13, and nQ19 gradients change to 4.26, 13.56, 13.56 T/m, respectively. In terms of current this means shunting ~140-150 A around the nQ07, while adding ~70-75 A to the nQ13, nQ19 quadrupoles.

CONCLUSIONS

The Fermilab Delivery Ring optics can be configured to decelerate beams from the design energy of 8 GeV down to ~1-2 GeV while avoiding crossing transition. With modest modifications to the powering of select quadrupoles in the lattice, transitionߛ��௧ can be boosted above the beam Ȗ for all energies. For beam Ȗ values that are below ߛ௧ ൌ ǤͶ (the design transition energy value) by more than 0.5 units, the lattice optics revert to design values.

REFERENCES [1] REDTOP: Rare Eta Decays with a TPC for Optical Photons,

http://redtop.fnal.gov/

Side Note: the LHC

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MostofcircumferencemadeofFODOcells

8major“straightsections”,usedforinjection,extraction,acceleration,etc.,andforinteractionregions(collisions!)

Electron Injector Linac Optics§ IOTA (Fermilab)

• IOTA: FACILITY AND EXPERIMENTAL BEAM PHYSICS PROGRAM, JINST 12 T03002—2017, S. Antipov, D. Broemmelsiek, D. Bruhwiler, et al

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– 8 –

2.2 IOTA electron injector

The IOTA electron injector comprises a number of components, including a 5 MeV electron RF photoinjector, a 25-meter-long low energy (≤50 MeV) beamline and a ~100-meter-long high energy (≤300 MeV) beamline. The optical functions of the injector are shown in Fig. 8.

The electrons are produced with a UV drive laser. The drive laser is based on a Calmar seed laser, consisting of a Yb-doped fiber laser oscillator running at 1.3 GHz that is then divided down to 81.25 MHz before amplification through a set of fiber amplifiers. The seed output of 81.25 MHz packets of 1054 nm infrared laser is then reduced to the desired pulse train frequency (nominally 3 MHz) with a Pockels cell, before selection of the desired pulse train with two additional Pockels cells and amplification through a series of YLF crystal-based single pass amplifiers (SPAs) and a Northrup-Grumman amplifier. All of this nominally yields 50 µJ of IR per pulse before two frequency-doubling crystal stages generate the green and then the final UV components with a total nominal efficiency of 10% [10]. The pulse train structure is selectable between a single pulse per IOTA beam cycle (nominally 1 Hz) and up to a 5 Hz, 1 ms long train of 3000 pulses at the nominal 3 MHz pulse train frequency, as shown in Fig.9. The UV (263 nm) drive laser pulse train is used to generate an electron pulse in the IOTA electron injector, which is an SRF- based linear accelerator.

Figure 8: Optical functions of the 300 MeV IOTA electron injector linear accelerator. The origin is at the 5 MeV photo-injector cathode, and the beam ends at the high energy absorber.

The 5 MeV electron RF photoinjector is shown in Fig.10. The RF photocathode electron gun is identical to the guns recently developed at DESY Zeuthen (PITZ) for the FLASH facility [11]. It is a normal conducting 1½ cell 1.3 GHz gun operated in the TM010 π mode, with a QL of 11,700, driven by a 5 MW klystron. The power is coupled into the gun via a coaxial RF coupler at the downstream end. The gun is capable of an average DC power dissipation of 20 kW. A temperature feedback system will regulate cooling water temperature to less than ±0.02 °C, as required for good phase stability. The gun can be routinely operated at peak gradients of 40-45 MV/m, with