Amendment 1 - 7 TESLA CRYOMAGNET Questions.pdf

7 TESLA CRYOMAGNET – 1333ND20QNB610474 – Questions with Responses

General Note: This requirement is for a complete and functioning Cryomagnet system. Offerors interested in this project have been directed, in the Statement of Work, to submit a Conceptual Design for their proposed system. There is no expectation of a near-completion, detailed plan/schematic of the proposed system during the solicitation response period.

The conceptual design is intended to be a generalized plan of action, in accordance with the Solicitation package (Statement of work, attachments and any amendments/Q&A), and consists of:

- An outlined summary of the steps a vendor will propose to accomplish the project goal.

- A list of deliverables.

- A list of any equipment (major and ancillary), with model numbers, necessary to manufacture the complete

7 Tesla superconducting magnet system.

- A list of any subset equipment being outsourced.

- A high-level estimated timeline (draft Gantt chart) to be delivered with the quote response. Further refinement of the Gantt chart will be developed after award.

Evaluations will be conducted on this design and the information provided to demonstrate the ability for the design to successfully fulfil the needs of this requirement. The finalization of this design and implementation of the manufacturing process will follow any award resulting from this solicitation.

Reference Question with Response

Page 4, Due date for quotations

The requirement SOW is a complex, custom-designed system. As such it requires a priori superconducting magnet design. We therefore request a minimum extension of 6 weeks to the August 25, 2020 date (i.e. to October 06, 2020) in order that the necessary design work and diligence can be applied. Please also note the reliance upon the provision of further information from NIST in this regard as critical design inputs, including responses to these questions.

RESPONSE: NCNR must make an award by 30 September 2020 to avoid losing the money for this requirement. We will grant an extension to 10 September 2020 at 2PM EDT. (see General Note above)

General There are likely to be design trade-offs which will require NIST feedback for optimization.

Please indicate if/how this may be possible – for example, is technical dialogue possible?

RESPONSE: Once an award has been made and a proposed conceptual design has been selected, there would be discussion between the NCNR technical team and the chosen vendor to optimize the final design (and manufacturing of the cryomagnet system).

Background Is a vendor requirement implied by “safeguards to protect both the equipment and personnel during operation”? For example, interlocks?

RESPONSE: Yes. Protection from runaway magnetic field, vacuum space overpressure safeguards, overtemperature safeguards for samples and magnet, and other such safeguards that would be necessary to protect equipment and personnel. Proximity interlocks will not be required from the vendor, for example.

Reference Question with Response

System Description Please confirm that the term “sample positioner” used here and elsewhere in the document refers to what would normally be called a “sample stick” or “sample rod”, i.e. the assembly which holds the sample at the beam/magnet position within the variable temperature insert.

RESPONSE: Yes, sample positioner can be used synonymously with sample stick or sample rod. It is the stick which puts the sample into position within the VTI, but which is neither the 3He insert nor the dil fridge.

5.1.3 Will NIST also provide the 3He gas for the helium-3 dipper? Please note that 3He purity requirements for the helium-3 dipper are higher than for the dilution refrigerator.

RESPONSE: Yes, NIST will provide all 3He gas required.

5.1.4 The dimensions of the existing NCNR dilution refrigerator inserts are required as a design input. Please provide these at the earliest opportunity, including detailed of the position of the 1 K pot and heat exchangers.

RESPONSE: Dimensions provided in the original attachments reflect the dimensions of the existing dilution refrigerator. Once an award has been made and a proposed conceptual design has been selected, we will provide any and all additional dimensions requested by the vendor to ensure a match.

5.2.1 Please comment further on the restriction to air-cooled compressors. This restriction significantly limits the choice of pulse tube refrigerator which can be used on the system and may lead to significantly higher costs and higher electricity consumption with two low-power coolers rather than one high-power. Please also note that for the 12 T system, chilled water will be required for its dilution refrigerator turbo pump(s).

RESPONSE: Chilled water for any components is not acceptable. GM style cryocoolers with sufficient cooling power are on the market that run on air-cooled compressors. NIST currently has a system such as this that sufficiently cools our 10T magnet. However, NIST does not oppose the use of Pulse Tube cryocoolers in the design of new 7T magnet system.

(note: this answer relates solely to the 7T Cryomagnet. Responses to questions relating to the 12T requirement can be found with that solicitation)

5.2.2 How much height adjustment of the sample is required?

RESPONSE:

Dilution Refrigerator: 5.3.6 The vacuum flange of the insert must provide flexibility to manually adjust the insert's vertical position by up to +/- 30mm …

Helium-3 Dipper: 5.4.6 The vacuum flange of the dipper has to provide flexibility to manually adjust the insert's vertical position by up to +/- 30mm …

Sample Stick: Was not specified explicitly in the SOW, but should also be +/- 30mm.

Remotely controlled vertical adjustment: Table under 5.10.3: Vertical adjustment range:

Minimum 10mm, maximum 15mm.

5.2.7 Please expand on and quantify this requirement for a “center tap to allow small vertical offset of the magnetic field center”. What distance is the offset and in what direction (up/down)? Is this expected with the magnet in persistent mode? What is the intention for this capability; for example, is the requirement actually to allow both a symmetric and asymmetric field pattern?

RESPONSE: The asymmetry should be 20 %. The intention of this requirement is to allow polarized neutrons to pass through the sample position without depolarization due to the center of the magnetic field.

5.2.11 What neutron absorbing material is required? (material and thickness)

RESPONSE: Any neutron absorbing material excluding cadmium is acceptable.

5.2.12 What grades of Aluminum/Al alloy are acceptable?

RESPONSE: 6061 is typical, other low Cd content alloys are acceptable; 4000, 5000, and 6000 series alloys.

5.2.15 How have the maximum axial and lateral forces on the magnet been calculated, without having the actual magnet model? Can the environment information be provided so that the vendor can perform their own calculations and identify any trade-offs, using the actual magnet design model?

RESPONSE: NCNR has a number of superconducting magnets and have done the calculations based on prior experience. Once an award has been made and a proposed conceptual design has been selected, NIST will work with the vendor to refine the models for the final design.

5.2.15 Please clarify the requirement for “no magnetic materials”. Stainless steel is typically an essential structural material in such systems, and while nominally non-magnetic does typically contain some residual magnetic traces.

RESPONSE: Materials that will have a relative magnetic permeability in the range from 1.000 to 1.01 when measured at magnetizing forces of 200 Oersteds (16k A/m). Non-magnetic materials near the sample position/beam path are important to prevent depolarization of the neutron beam.

5.2.15 Polarized beam requirement – this is typically incompatible with the symmetric field magnet specified. Is this the purpose of 5.2.7? What is the depolarization factor specification?

RESPONSE: The system will be used in both polarized and non-polarized neutron experiments. For non-polarized neutrons, a symmetric field magnet is required. For polarized neutrons an offset is required. The depolarization factor specification is 20%.

5.2.15 What is the over-arching driving requirement between magnetic field, azimuthal angle, and the stated maximum dimensions? i.e. to which specification should the vendor target their design optimization?

RESPONSE: The stated maximum dimensions are hard limits to ensure fit within the existing instrument enclosures. Azimuthal angle and field are as specified in the SOW.

5.3.2 The details of NCNR’s existing 10 T magnet are required as a design input. Please provide these, including VTI dimensions, position of VTI heat exchanger, VTI cooling power at 2 K, and VTI entry flange type.

RESPONSE: VTI dimensions and flange types were accounted for in the original attachment.

NIST will provide any further dimensions to refine the design after award.

5.4.2 The details of NCNR’s existing 10 T magnet are required as a design input. Please provide these, including VTI dimensions, position of VTI heat exchanger, VTI cooling power at 2 K, and VTI entry flange type.

RESPONSE: VTI dimensions and flange types were accounted for in the original attachment.

NIST will provide any further dimensions to refine the design after award.

5.4.8 For the helium-3 dipper, a “Cooling Power @100mK” of 120 microwatts is stated. However, the base temperature will not be below 250 mK. Please clarify/correct.

RESPONSE: [Correction] Cooling power requirement for the 3He dipper was listed in error and is removed from the specifications/requirements.

None Is there a/what is the weight limit for the system on the goniometer?

RESPONSE: 400 kg

None As these inserts typically only reach 290mK then this must be an error. Our He3 inserts would typically specify 50uW cooling power @ 350mK. However, they regularly achieve this at 325mK.

Can you confirm what you need the cooling power to be on the He3 insert please.

RESPONSE: [Correction] The “cooling power” line in the table for the 3He Dipper is deleted.

This spec for the 3He Dipper should not include the cooling power requirement at all. The base temperature, cooling time, hold time, etc. are sufficient to specify the cooling.

Due Date This is an unreasonably fast turnaround and we request an extension of at least 7 days, for not less than 14 days after clarifications are released for preparation of the tender submission.

RESPONSE: NCNR must make an award by 30 September 2020 to avoid losing the money for this requirement. We will grant an extension to 10 September 2020 at 2PM EDT.

Submission Please clarify if there are any email format or firewall concerns for this submission. Per specifications in Quotation Preparation Instructions, we understand that five independent PDF documents should be provided, with cross-references as necessary. If any file size restriction exists, accommodations can be made.

RESPONSE: The NIST maximum size of a file is 25MB per email.

5.1.1 Please confirm this requirement is for conduction-cooled cryogen free operation only; the phrase ‘…use of an initial charge of helium gas to initialize a self-cooling cryogenic system…’ appears to allow for a re-condensing liquid helium cryostat type.

RESPONSE: The system must be operable continuously with no initial or ongoing charge of LIQUID cryogens. This does not preclude gaseous helium from condensing within the system as needed for cooling the VTI.

5.2.11 Please define ‘…near…’. This needs to be specified more clearly. We plan to place cd shielding to protect the surface of the magnet exposed to the beam-path but confirm this cd shielding will not impede the other related requirements (split, vertical access, azimuthal access).

RESPONSE: This is a radiation safety requirement due to high prompt-gamma radiation in cadmium exposed to neutrons. Cadmium is not permitted because Cadmium will cause a radiological safety concern because of elevated prompt-gamma radiation

5.2.15 Please clarify the magnet performance requirements (homogeneity, 5G line, split and vertical angle), as these are in conflict according to our technical evaluation. Does NCNR have any potential concession in the magnet requirement? Meeting what appear to be the key requirements (outer diameter limit of cryostat, split & vertical angle, operating field 7T) makes homogeneity of 1 % in 2cm DSV not possible to achieve in our initial evaluation (the 0.6% in 1 cm dsv is achievable).

RESPONSE: No. There is not flexibility for consideration in either requirements.

5.2.2, 5.3.6, 5.4.6, and 5.10

Please clarify the intent of the differences in requirement for ‘…sample positioners…’ in 5.2.2, manual adjustment within sections 5.3.6 & 5.4.6, and the automated motorised adjustment requirements within sections 5.10, 5.10.1,5.10.2, and 5.10.3.

RESPONSE: Manual adjustment of the sample positioner is performed outside the cryostat and with the sample dimensions in mind, it is a large range of adjustment. Automated adjustment occurs within the cryostat and allows for refinement of the sample position and thus can be a smaller range.

5.5.1.4, 5.6.4.8 Please clarify over what range the temperature stability requirement ±500 mK applies, and to which components of the full system requirement (VTI, Dipper 3He, DR insert).

RESPONSE:

5.5.1.4 Is control stability of ± 500 mK for the magnet. This is correct.

5.6.4.8 This was an error. The ramping should be as low as 0.001 K/m and the control stability should be 10 microK at 50 mK.

5.6.1 and 5.4.8 The requirement for optimisation for < 50 mK control appears to contradict the section

5.4.8 minimum operating temperature of 50 mK. Please clarify.

RESPONSE: One section refers to the 3He Dipper and the other refers to the Dilution Refrigerator controller.

5.6.3.1 and 5.2.15 The linear-dependence requirement from 0 to 12T cannot be demonstrated with the ± 7 T magnet operating range requirement in section 5.2.15. Please clarify.

RESPONSE: [Correction] The range for this system is ± 7 T.

5.6.4.7 Please clarify the requirement for provision of source code for the dilution refrigerator.

RESPONSE: This requirement is to ensure that NCNR has full access to view and change all parameters for the dilution refrigerator. If such software is produced by the vendor for this system, then the source code is a deliverable.

5.7.2 The reference to the mixing chamber in a 3He dipper insert is not understood. Please clarify.

RESPONSE: [Correction] “mixing chamber” is replaced with “Pot”.

5.7.2.1 The requirement for a sensor with calibration from 0.02 to 40 K is not understood. Please clarify as this cannot be demonstrated below 0.3 K with a 3He dipper insert.

RESPONSE: Sensor’s manufacturer specifications must include calibration in this range.

5.7.2.4.1 The requirement for a magnetic field calibration at 50 mK is not understood. Please clarify as this cannot be demonstrated below 0.3K with a 3He dipper insert.

RESPONSE: Field calibration at the base temperature of the 3He dipper insert is acceptable.

5.7.2.7 Please clarify the temperature range over which the ±300 mK temperature stability must be demonstrated in the 3He dipper.

RESPONSE: [Correction] language in 5.7.2.7 is changed to: The temperature controller(s) ramp rate must enable the temperature on the sample to be linearly varied to cool or warm the sample at a user defined rate ranging from 0.1 Kelvin/min or lower to 5 Kelvin/min or larger and have a temperature stability of ± 50 microKelvin or better over the range 0.3 Kelvin to 4.2 Kelvin, and ± 300 milliKelvin from 4.2 Kelvin to 300 Kelvin.

5.9.2 Please clarify the lift test certification requirement. We routinely provide certified lift eyes/lift points, but do not hold a standard certification procedure. Please advise any standards to achieve with the trolley arrangement.

RESPONSE: If the vendor provides full engineering models for liftable items, including center of gravity modelling, and all calculations used to show why each certified lift point was chosen, then NCNR will accept this.

5.7.2.2 Requires a RuO2 calibrated between 0.02-40 Kelvin. Is this correct for the Helium 3 system as well as the dilution refrigerator, as suggested?

RESPONSE: Yes, this sensor requirement is still correct for the 3He dipper.

5.4.2 Requires that the He-3 Dipper must be compatible with the existing 10T magnet. Can you provide further details? Does this mean a 10T magnet in an existing cryostat? IF so, what is the sample space size of the 10T magnet system?

RESPONSE: Correct. 10T magnet system has a cryostat. The dimensions have been accounted for in the attachments to the solicitation.